[GL] Added ARB_clip_control
[GL][ES] Added tokens for backwards compatibility

The 4.5 spec moves BLEND_ADVANCED_COHERENT_KHR from
KHR_blend_equation_advanced to KHR_blend_equation_advanced_coherent.
Add a deprecated token to maintain binary compatibility.
[GL] Implemented ARB_cull_distance
[GL] Implemented ARB_conditional_render_inverted
[GL][ES] Implemented KHR_context_flush_control
[GL] Implemented ARB_get_texture_sub_image

Also fixed KHR_context_flush_control tokens in OpenGL ES.
[GL][ES] Implemented KHR_context_robustness
[GL] Added missing tokens for 4.2-4.4
[GL] Implemented ARB_direct_state_access

See http://www.opengl.org/registry/specs/ARB/direct_state_access.txt
[Bind] Allow multiple overrides files

Multiple overrides files allow us to split overrides by extension,
simplifying maintenance.
[GL] Added a missing enum
[Bind] Moved GL overrides to parent folder
[ES] Implemented bindings for ES 3.1 (1/2)

Implemented core functionality:
- KHR_compute_shader
- KHR_draw_indirect
- KHR_explicit_uniform_location
- KHR_framebuffer_no_attachments
- KHR_program_interface_queries
- KHR_separate_shader_objects
[ES] Implemented bindings for ES 3.1 (2/2)

Implemented core functionality:
- KHR_shader_atomic_counters
- KHR_shader_image_load_store
- KHR_shader_storage_buffer_object
- KHR_stencil_texturing
- KHR_texture_gather
- KHR_texture_storage_multisample
- KHR_vertex_attrib_binding
[ES] Typo corrections in the ES 3.1 bindings
[GL][ES] Implemented ARB_ES_3_1_compatibility

MemoryBarrier and MemoryBarrierByRegion now use the same enum name.
[ES] Implemented ES 3.1 binding generator
[GL] Added missing VertexAttribDPointerType enum

This enum used to be there, but somehow disappeared from the 4.5 specs.
It’s back now.
[GL] Removed duplicate bindings
[GL] Fixed TEXTURE_BINDING_RECTANGLE token