Tutorial updates

[Geokureli]

To coincide with https://github.com/HaxeFlixel/flixel-demos/pull/305:

• improve animation
• slow down movement speed
• improve hitbox

[Geokureli]

@SeiferTim I added some more things, and there is a coinciding change to the flixel-demo https://github.com/HaxeFlixel/flixel-demos/pull/305 no need to check that out, just posting in here for posterity