Organization of Mockups

Moved barrel, boulder, and pot to an "items" folder.
Moved land to the environment folder.
Please put things in their proper folders. If a folder doesn't exist for
what you are making, then make a new folder for it. Thank you!
-Travis
Deleted old gamefile

BL_ver01 is no longer needed.
-Travis
Added code for locked doors

Still a work in progress, does not work yet.
-Travis
Plea for Organization

Updated the contribute.md
-Travis