Add Game 2 Base Flixel Template

Just the baisc Flixel Template and a new directory name.
Update Project XML
Clean up Main.hx

The template includes several features we won't use and some boilerplate
that is redundant with the default OpenFL behavior.
Remove AssetPaths.hx

I just don't find this useful.
Add Button

Just a simple Button class for the many UIs I'll be creating in the next
three games.