Improve FlxColor documentation, closes #428

- `FlxColor`
 - Added docs to interpolation functions, which closes #428
 - Capitalized all params. Hope I got them all now!
 - A few random "asthetic" changes.
- `DebuggerFrontEnd`
 - Removed the word "debugger" from `setDebuggerLayout()` and `resetDebuggerLayout()`