KHRONOS: Fix XML
dispatch: Generate piglit-dispatch from gl.xml

TODO(chadv): Explain my changes to Fabian's patch.
TODO(chadv): regression test
TODO(chadv): review Fabian's patch in more detail

The .spec files which were previously used are no longer maintained.
Khronos advises to migrate to the XML Registry.

Note: This breaks the arb_multisample-pushpop test as it expects
GL_ALL_ATTRIB_BITS not to include GL_MULTISAMPLE_BIT as the extension spec
mandates. gl.xml defines GL_ALL_ATTRIB_BITS to include GL_MULTISAMPLE_BIT
as GL 1.3 and later specs say.

Signed-off-by: Fabian Bieler <fabianbieler@fastmail.fm>
glapi: Kill unused glapi files

TODO(chadv): Commit message
dispatch/gles1: Use piglit-dispatch for GLES1 tests

STATUS: Piglit builds with no new warnings
TODO: commit message
TODO: regression test
dispatch: Improve usability of generator script

TODO: commit message
WIP dispatch: Refactor Api.generate_code

TODO: Commit message

Rename the following:
    Api.generate_code -> Api.generate_dispatch_code
    c_contents        -> dispatch_c
    h_contents        -> dispatch_h

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
WIP dispatch: Refactor class Enum
WIP dispatch: Add Api.compute_unique_nonbitmask_enums
wip: enums