Fix typos (#435)

```
codespell **/*.rb **/*.md -w -L doesnt
```

Plus manual fixes

CHANGELOG.md

@@ -265,7 +265,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 **Closed issues:**
 
 - DEPRECATION WARNING on rails 5.0 as of acts\_as\_list 0.9 [\#251](https://github.com/brendon/acts_as_list/issues/251)
-- highter\_items returns items with the same position value [\#247](https://github.com/brendon/acts_as_list/issues/247)
+- higher\_items returns items with the same position value [\#247](https://github.com/brendon/acts_as_list/issues/247)
 - Broken with unique constraint on position [\#245](https://github.com/brendon/acts_as_list/issues/245)
 
 **Merged pull requests:**
@@ -493,7 +493,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix sanitize\_sql\_hash\_for\_conditions deprecation warning in Rails 4.2 [\#140](https://github.com/brendon/acts_as_list/pull/140) ([eagletmt](https://github.com/eagletmt))
 - Simpler method to find the subclass name [\#139](https://github.com/brendon/acts_as_list/pull/139) ([brendon](https://github.com/brendon))
 - Rails4 enum column support [\#130](https://github.com/brendon/acts_as_list/pull/130) ([arunagw](https://github.com/arunagw))
-- use eval for determing the self.class.name useful when this is used in an abstract class [\#123](https://github.com/brendon/acts_as_list/pull/123) ([flarik](https://github.com/flarik))
+- use eval for determining the self.class.name useful when this is used in an abstract class [\#123](https://github.com/brendon/acts_as_list/pull/123) ([flarik](https://github.com/flarik))
 
 ## [0.5.0](https://github.com/brendon/acts_as_list/tree/0.5.0) (2014-10-31)
 [Full Changelog](https://github.com/brendon/acts_as_list/compare/0.4.0...0.5.0)
@@ -633,7 +633,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - acts\_as\_list :scope =\> "doesnt\_seem\_to\_work" [\#12](https://github.com/brendon/acts_as_list/issues/12)
 - don't work perfectly with default\_scope [\#11](https://github.com/brendon/acts_as_list/issues/11)
 - MySQL: Position column MUST NOT have default [\#10](https://github.com/brendon/acts_as_list/issues/10)
-- insert\_at fails on postgresql w/ non-null constraint on postion\_column  [\#8](https://github.com/brendon/acts_as_list/issues/8)
+- insert\_at fails on postgresql w/ non-null constraint on position\_column  [\#8](https://github.com/brendon/acts_as_list/issues/8)
 
 **Merged pull requests:**
 
@@ -642,7 +642,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Massive test refactorings. [\#24](https://github.com/brendon/acts_as_list/pull/24) ([splattael](https://github.com/splattael))
 - Silent migrations to reduce test noise. [\#22](https://github.com/brendon/acts_as_list/pull/22) ([splattael](https://github.com/splattael))
 - Should decrement lower items after the item has been destroyed to avoid unique key conflicts. [\#18](https://github.com/brendon/acts_as_list/pull/18) ([aepstein](https://github.com/aepstein))
-- Fix spelling and grammer [\#15](https://github.com/brendon/acts_as_list/pull/15) ([tmiller](https://github.com/tmiller))
+- Fix spelling and grammar [\#15](https://github.com/brendon/acts_as_list/pull/15) ([tmiller](https://github.com/tmiller))
 - store\_at\_0 should yank item from the list then decrement items to avoid r [\#14](https://github.com/brendon/acts_as_list/pull/14) ([aepstein](https://github.com/aepstein))
 - Support default\_scope ordering by calling .unscoped [\#13](https://github.com/brendon/acts_as_list/pull/13) ([tanordheim](https://github.com/tanordheim))
 

README.md

@@ -5,7 +5,7 @@
 [![Gem Version](https://badge.fury.io/rb/acts_as_list.svg)](https://badge.fury.io/rb/acts_as_list)
 
 ## ANNOUNCING: Positioning, the gem
-As maintainer of both Acts As List and the Ranked Model gems, I've become intimately aquainted with the strengths and weaknesses of each. I ended up writing a small scale Rails Concern for positioning database rows for a recent project and it worked really well so I've decided to release it as a gem: [Positioning](https://github.com/brendon/positioning)
+As maintainer of both Acts As List and the Ranked Model gems, I've become intimately acquainted with the strengths and weaknesses of each. I ended up writing a small scale Rails Concern for positioning database rows for a recent project and it worked really well so I've decided to release it as a gem: [Positioning](https://github.com/brendon/positioning)
 
 Positioning works similarly to Acts As List in that it maintains a sequential list of integer values as positions. It differs in that it encourages a unique constraints on the position column and supports multiple lists per database table. It borrows Ranked Model's concept of relative positioning. I encourage you to check it out and give it a whirl on your project!
 
@@ -290,7 +290,7 @@ All versions `0.1.5` onwards require Rails 3.0.x and higher.
 
 We often hear complaints that `position` values are repeated, incorrect etc. For example, #254. To ensure data integrity, you should rely on your database. There are two things you can do:
 
-1. Use constraints.  If you model `Item` that `belongs_to` an `Order`, and it has a `position` column, then add a unique constraint on `items` with `[:order_id, :position]`.  Think of it as a list invariant. What are the properties of your list that don't change no matter how many items you have in it?  One such propery is that each item has a distinct position. Another _could be_ that position is always greater than 0. It is strongly recommended that you rely on your database to enforce these invariants or constraints. Here are the docs for [PostgreSQL](https://www.postgresql.org/docs/9.5/static/ddl-constraints.html) and [MySQL](https://dev.mysql.com/doc/refman/8.0/en/alter-table.html).
+1. Use constraints.  If you model `Item` that `belongs_to` an `Order`, and it has a `position` column, then add a unique constraint on `items` with `[:order_id, :position]`.  Think of it as a list invariant. What are the properties of your list that don't change no matter how many items you have in it?  One such property is that each item has a distinct position. Another _could be_ that position is always greater than 0. It is strongly recommended that you rely on your database to enforce these invariants or constraints. Here are the docs for [PostgreSQL](https://www.postgresql.org/docs/9.5/static/ddl-constraints.html) and [MySQL](https://dev.mysql.com/doc/refman/8.0/en/alter-table.html).
 2. Use mutexes or row level locks. At its heart the duplicate problem is that of handling concurrency. Adding a contention resolution mechanism like locks will solve it to some extent.  But it is not a solution or replacement for constraints.  Locks are also prone to deadlocks.
 
 As a library, `acts_as_list` may not always have all the context needed to apply these tools. They are much better suited at the application level.