v1.4 Bug fixes and IntGrids

• Fixed a couple bugs with loading entity fields, cleaned up the code and organized it better
• Changed the project/local package file structure
• Added more prefixes to the config for tilesets, layers and fields
• IntGrids are now loaded into a global struct as instances of a custom Grid constructor
• Added an option to the config to ignore IntGrids when loading the level
• Added a new entity/object to the demo to showcase entity ref fields and arrays of points