This adds a new module in the generated_tests/modules directory, which
contains three classes, GLSLVersion, GLSLESVersion, and Version. Version
is a factory that caches other versions and makes GLSLVersion and
GLSLESVersion instances on demand.

The goal of these classes is to provide a simple, unified method for
dealing with GLSL version numbers, which is something that a lot of
generators need to do. To that end it provides rich comparisons against
each other and against ints and floats. The hope is that other generator
writers could leverage this work in their generators to simplify things.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Acked-by: Ilia Mirkin <imirkin@alum.mit.edu>