Added Keys class Enum

Created a new enumerated class Keys (int) to represent keyboard keys.
Included print-to-file and print-to-ui methods.
Convenience template for initializing a map.

Template function initializes a map with key/value pairs. Based on this
stackexchange answer by MSalters here:
http://stackoverflow.com/questions/207976/how-to-easily-map-c-enums-to-strings
Moved Keys enum to its own implementation
Added keys.o to object list