Customizable Player Models

Added hold to play gesture/pose mode
Added non looping gestures reset after playing
Improved Gesture gui on big gui scales
Added new poses:

• In Menu
• First Person Model View

Added new type of animation: Layers (Closes #64)
Added an updated gesture system when mod is installed on the server (Closes #66)
Updated Simplified Chinese translations (#276)

Fixed settings popup/gui always asking to discard changes
Fixed some popups opening way too big with some gui scales
Fixed Optifine breaking Glowing parts (Closes #278)
Fixed skull rendering when the First Person Model mod is installed
Fixed model loading status rendering in the wrong place in some cases