Updated legacy sprite engine with latest features and fixes

[TheRoboZ]

This implements:

• SPR_setAlwaysAtBottom
• SPR_setAutoAnimation
• SPR_getAutoAnimation
• SPR_setAnimationLoop
• SPR_getAnimationDone

and fixes the empty frame bug in:

• static void loadTiles(Sprite* sprite)

for the legacy sprite engine

[D0NM]

COOL!
Alas, we keep using our own wrapper around the basic SGDK funcs because even now it is not enough for a beat 'em up

[TheRoboZ]

Any chance of sharing the wrapper? This PR came from a plan to compare bot sprite engines for performance on r-type, if your wrapper performs even better, I'd gladly use it for an ad-hoc implementation for my engine.

[D0NM]

Any chance of sharing the wrapper? This PR came from a plan to compare bot sprite engines for performance on r-type, if your wrapper performs even better, I'd gladly use it for an ad-hoc implementation for my engine.

We cannot share it (at least until Zabu is fully released). But the main thing in the wrapper is:

• Animations have some meta data
• Each frame animation has its own duration

[Stephane-D]

Approved :) Thanks for your contribution !