Mouse and Keyboard implementation

Supports callbacks for:
- all keyboard buttons
- mouse position
- left and right mouse buttons
Support for find key by char (not working)

Attempted to add support for finding the value of a keyboard button
using a character parameter. I can't figure out how to properly define
an object of HKL type, which is necessary to convert characters to
Vitual Key Codes. Also included a demo of the input system
Updated git ignore
Removed tracking of old files that should be ignored