I've added .PHONY targets and fixed "clean" recipe.

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.

if mesh is not loaded properly it breaks the game!

Finally, physics update is handled in main thread using steps to get
accuracy in collisions detection instead of moving it to a new thread.

Examples are finished as simple and clear as I could. Finally, physac
module is MORE simpler than in the first version, calculation everything
by the same way for both types of physic objects.

I tryed to add rotated physics a couple of times but I didn't get
anything good to get a base to improve it. Maybe for the next version...

No bugs or strange behaviours found during testing.

...despite not being enabled on GLFW3

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

Depth test disabled for 2D and only used on 3D; consequently LINES vs
TRIANGLES vs QUADS buffers drawing order maters... but blending also
works ok.

Now it works ok also in RaspberryPi

physac module base almost finished. All collisions are now resolved
properly and some force functions was added.

COLLIDER_CAPSULE removed for now because in 2D everything is composed by
rectangle and circle colliders...

The last step is move physics update loop into another thread and update
it in a fixed time step based on fps.

I've renamed all makefile files to "Makefile" because they appear in the first files.

change name variable

To support multiple keys (including function keys)

Requires Shader access functions review

physac modules is being redesigned. Physics base behaviour is done and
it is composed by three steps: apply physics, resolve collisions and fix
overlapping.

A basic example is currently in progress. The next steps are try to add
torque and unoriented physic collisions and implement physics basic
functions to add forces. Rigidbody grounding state is automatically
calculated and has a perfect result. Rigidbodies interacts well with
each others.

To achieve physics accuracy, UpdatePhysics() is called a number of times
per frame. In a future, it should be changed to another thread and call
it without any target frame restriction.

Basic physics example has been redone (not finished) using the new
module functions. Forces examples will be redone so I removed it from
branch.

Specially useful on default font scaling

- Check if first character is the expected Space char (32)
- Check if characters are ordered in definition file (.fnt)

- Removed DrawQuad() function
- DrawBillboard() uses DrawBillboardRec()
- DrawPlane() uses RL_TRIANGLES
- DrawRectangleV() uses RL_TRIANGLES, that way, [shapes] module uses
only TRIANGLES buffers.