Vscode extension packaging

[Goju-Ryu]

This PR sets up the vs-code extension to make it easy to package.

I also added and changed a few things:

• Replaced template text in README with text relevant the numbat extension
• Added extension Icon
• Used numbat icon for numbat files
• Added license, repo, and homepage information
• Added keywords
• Redesigned how string highlighting is passed (this fixes some highlighting bugs and adds support for multi line strings)

What it looks like:

[Goju-Ryu]

Installing it is very easy and can be summed up in a single picture:

Click Install from VSIX... select the VSIX file in the file selector that pops up and it is automatically installed.

That said, it is currently not easy to get the VSIX file without getting the repo and creating it for yourself. I am not sure what the best way to solve it is, but an easy solution is to release it with the other numbat assets in each release. I will update the README and Numbat documentation to reflect how we distribute the VSIX when we have decided.