Upgrading to 1.3

The upgrade to 1.3 adds a number of new features to Platformer Plus:

• Moving platforms have been made more stable/usable.
• Added a float-ability
• Added options for how running is handled other than the default smooth acceleration.
• Added toggles for air-control and wall-slide. 
• An option to add horizontal or vertical momentum to the dash ability

Perhaps more importantly, though, this update has introduced a number of behind the scenes changes to remove bugs and improve the code's performance. I'm not going to have much chance to make any big changes for a while, so I wanted to make this version as useful and stable as possible!