Crash Fix:  Global set_animation is nil when trying to ride a dragon.

Change to mobs:set_animation fixes this.

Modernize code: Replace deprecated function calls

Fixed deprecated calls. Tiny whitespace cleanup.

remove conditional around first dragon

Dragonplus

* Added piloting to normal dragons
* Load dragon arrows always

* Split piloting functions to a separate file
* switched from lib_mount driving to object_fly

Cleanup