Release 2.8.4 - Simplified API

This release simplifies some of the most common operations, adding replacement functions with less parameters or making some of the old required parameters as optional. Old functionality is deprecated but available, to retain backwards compatibility

• Deprecates old TLN_SetLayer() that required passing a NULL tileset, and replaces with new TLN_SetLayerTilemap() that just requires the tilemap handler
• TLN_SetLoadPath() not needed anymore: chain loading of resources being loaded from subdirectories is supported (.tmx -> .tsx -> png)
• TLN_DrawFrame() / TLN_UpdateFrame(): frame parameter can be always 0, in that case it auto-increments internally. Application doesn't need to keep track of frames just to make the animation engine work.
• Updates many samples to use current features, making them easier to follow

Also online documentation is updated with a new "Tutorial" section and reworked "Layers" section