Added a bunch of courses, along with some more items and jobs.
Merge pull request #90 from ChodeGames/endgame

Added endgame conditions
Added a few more items.
Converted double-digit numbers to letters
Fixed traceback with a letter as course symbol.

This changes get_course_by_number to get_course_by_symbol, which is more in line with some of the other methods of location.py. The course symbols are now all strings (even though they are numbers for courses 1-10).
Implemented consumable property for items.

For any item with a consumable flag of true (default), when the item is used, it is removed from the player's inventory. For non-consumable items, the item stays in the inventory after using it.
Merge pull request #92 from ChodeGames/townville_map

Townville map
Merge branch 'master' into item_usability

Conflicts:
	game.py
Merge pull request #94 from ChodeGames/item_usability

Item usability
Update README.md

Adding link for Pygame install
Ignoring py files with tilde after filename.