add a Pegasus, jump bar to control flap

Add a pegasus mob. 

make the jump bar (hold the button to control the bar size) control the flap power. Since the animal is in control once the flap is complete the pegasus will just glide itself unless more flap is added. 

pegasus do not spawn like normal animals, must be freed from structures and only spawn once per structure that normally houses them (like allay). Probably found in the end. Pegasus can breed.

Pegasus stats vary like horses, but instead of higher jump, pegasus get a more or less powerful flap.