cmake: drop sparsehash_new module

It was a workaround for a buggy version of the lib.
gsdx-gles: nvidia driver quick trial (only GLES3.0)

* Fix to create a 3.0 GLES context
* set a default precision to fix most of shader compilation issue
* Crash later because of GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT
    => need to test opensource driver
license: add missing header

Still miss lots of copyright header but we are better