prevent hippy sliding when hurt, ensure all enemies use velocity instead of position
fix issue with humbug code
update enemies to use a speed property rather than have the values in the update function
manicorn stops when hit, add ducky and wasabi speed
do not add duplicate keys to inventory
Hide number of keys (always 1)
Merge pull request #2133 from CalebJohn/key-dropping

Dropping keys
Merge pull request #2130 from CalebJohn/hippy-slide

Have enemies modify velocity rather than position.