This fixes issue #360.

Also, improve variable names. This grew to be overly hard to understand.

Suggest gl_[Vertex,Instance]Index when gl_[Vertex,Instance]ID is encountered in Vulkan GLSL

See issue #350 for detail.  This may be an ESSL specification issue.

HLSL: Change intrinsics tests to not use overloaded entry points

When parsing Vulkan GLSL, suggest gl_VertexIndex/gl_InstanceIndex instead of gl_VertexID/gl_InstanceID.

SPV: Certain decorations are missing for structure-typed in/out variables

HLSL: Add asdouble, fma, & mad intrinsics 

Remove duplicated tests from the runtests script.

Basic (component) type conversion was done, but checking that the composite
was correct was not being done.

Fixes issue #353.

This is to make the real change needed in the next commit easier.

Symbol table sharing has different sets of symbols for different
versions. This needs to take into account that SPIR-V has different
symbols than non-SPIR-V.

HLSL: Add lerp, fix sincos ret, add ret type tests, non-square mats, tx semantics

Front-end: allow max size built-in arrays like gl_ClipDistance

Fixed off-by-one error with gl_MaxClipDistances and similar limits.

Add HLSL memory barrier intrinsics, fix dst, add lit & EvaluateAttrib…

This lets ES shaders use non-constant initializers for non-constant globals.

SPV doesn't allow gaps in the components of the texturing coordinate.
It also removes the shadow reference.
So, close up the components so all used components are together.

A barrier (ESSL/GLSL) or OpControlBarrier when in a tessellation control
shader also means doing memory synchronization for output variables.

HLSL: Implement atomic ops, bit conversions, fix minor intrinsics bugs

Build: Tracking allocator must use const key

Fixes TMap template.

This is required to build with newer libc++ versions that have a static
assert on const-ness of value_type