Lots of corrections.

- A way to case/match on Rgba (unapply).
- Changed (anew!) the orientation of textures, it should be correct
according to the OpenGL specs -> lower-left pixel is at (0,0) in UV
coordinates.
- Modified the plane mesh UV according to the texture.
- Added an experimentation to load game levels from ASCII art.
- Modified Armature and documented it.
- Modified TileSprite for UV change.
- Added a new SVGArmatureLoader able to load an Armature from a SVG
file prepared using Inkscape to ease the animatable characters creation.