Added SpriteCorral GUI object

The SpriteCorralMorph provides a container for sprite icons
Committing changes to crops.js to avoid a merge conflict.
Merge branch 'master' into Byron-Dev-Branch

Conflicts:
	system_models/crops.js

OK, now I fixed the merge.
Refactored Widgets into separate files in own directory

Attempting to improve organization/readability of code by splitting up
large files into class-specific files.
Merge branch 'master' of https://github.com/zombiepaladin/FarmSim
Implemented the sprite_corral_morph.js with the rest of the system_models.

Fixed the hide/show bug with sprite_corral_morph.js.