Updated

Integrate Develop branch

Update Makefile of 'src/' folder

The builds refer to de865a9 commit.

This library is only required by physac module to compulte physics in a
second thread

This commit restores the original method to compile all modules, but fix
prerequisites.

Replaced by example rlgl_oculus_rift

The first target allow makefile to install the dev files (static library and
header) to standard directories on GNU/Linux platforms; the second allow it to
unistall (remove) the dev files.

It needs lot of improvements.

Set makefile to default OpenGL 3.3 compilation

Develop branch integration

Some review work still required...