General Fixes + Refactor Color Handling

[Web-eWorks]

Couple of fixes / minor features:

• getRelativeMouseState was returning nothing
• We now have support for SDL_SetHintWithPriority, via an optional param in SDL.setHint()
• Minor updates on a couple of tutorials
• Code using libcommon can now push hex colors to Lua with videoPushColorHex

I unified how the library takes colors from Lua code, and deprecated videoGetColorHex. In theory, all hex-encoded values taken from Lua are interpreted as ARGB8888, without user code having to do anything.

The only place where videoGetColorHex was being used was in surface:fillRect/surface:fillRects, and there's handy access to SDL_MapRGBA() and the needed pixel format pointer there.

[Web-eWorks]

And done. Incidentally, I tested this on a couple of different surface types (BGRA4444, BGR565, BGR888, ABGR/BGRA/ARGB/RGBA8888), and color handling stayed the same (with the obvious difference in alpha channel presence, of course).