Moved all external libraries used by raylib to external folder inside
raylib src. Makefile has already been update and also the different
includes in raylib modules.

Internal modelview and projection matrices can be replaced before
drawing.

This is a first step toward a bigger project. Some modules could be
ported to header-only to be used as standalone.

Tint color could be applied to colDiffuse... but what's the best way?
Replace it? Multiply by? A point to think about...

Functions renamed to improve library consistency

It tints all fragments, ignores lighting. Useful for some features like
feedback (damage color, ...).

Scaling normal depth (y axis) makes disappear the specular of
fragments... So I think it can be removed, it is not a very
useful/important attribute.

Support render texture size different than screen size

Now shader maps use a generic naming convention for any kind of texture
maps (not only diffuse, normal or specular). Useful for custom shaders.

- 3 light types added (point, directional, spot).
- DrawLights() function added using line shapes.
- Standard lighting example added.
- Removed useless struct variables from material and light.
- Fixed light attributes dynamic locations errors.
- Standard vertex and fragment shaders temporally added until rewrite it
as char pointers in rlgl.
TODO:
- Add normal and specular maps calculations in standard shader.
- Add control structs to handle which attributes needs to be calculated
(textures, specular...).
- Adapt standard shader to version 110.
- Rewrite standard shader as char pointers in rlgl.

- Ambient and lambert lighting added.
- Ambient and diffuse colors linked to standard shader.
- Single light linked to standard shader.
- LoadStandardMaterial() and depending functions added.

...on model drawing

Improved materials

Keep asking myself why I maintain this rendering path... -___-

Depending on mesh data, it can be loaded and default vertex attribute
location points are set, including colors, tangents and texcoords2

- Renamed some functions for consistency (default buffers)
- Removed mystrdup() function (implemented inline)
- Renamed TextFileRead() to ReadTextFile()

Improve DXT-ETC1 support on HTML5

Only defaultShader required, set default value for vertex color
attribute if not enabled and fragColor uniform

Now it's possible to render to texture, old postprocessing system will
be removed on next raylib version.

...despite not being enabled on GLFW3

Redesigned to work as standalone and support fordward-compatible context
(shaders review)