* Support for automap options
- Added glslang_shader_options_t with enums for auto map bindings and
auto map locations.
- Added options param to glslang_shader_parse.
- Modified glslang_shader_parse to call appropriate auto map function if
auto map bits are set.
* Refactored auto map for C interface
- Added glslang_shader_set_options to independently set options instead
of being a param on an existing function.
- Added glslang_program_map_io to call mapIO so auto map location
actually works.
* Added support for shifting resource bindings
- Added resource binding shift functions to match C++ interface
* Uncommented preprocessor call that was commented out for debugging
* Introduces builtin variables gl_SecondaryFragColorEXT and gl_SecondaryFragDataEXT
* Introduces builtin constant gl_MaxDualSourceDrawBuffersEXT
* enables support for layout qualifier "index" in es profile
