Prepared project for JSON loading implementation.
mend
Added JsonCpp library in Linux project.
Migrated from Sprite class to SpriteSheet.

The new class have better extender features and optimizations.
Removed legacy class Sprite and modified DebugState to use the new class.
Fixed problem with incorrect Sprite Animation changing.
Added JSON files for reamining images in the assets folder.
Fixed problem with key input in DebugState.