HLSL: add precise keyword

Next step is to modify for HLSL rules.

This is part of the change to have desktop shaders respect precision
qualifiers on Vulkan, but since the defaults are all highp, and that's
different from ES fragment shaders, detect likely cases and warn about
them (but being careful to not be too noisy if it's unlikely to be a
problem).

Sets highp defaults for the appropriate types, for all stages,
and turns on precision qualifiers for non-ES shaders.  Required
fixing some qualifier orders for desktop built-in declarations
for pre-420 shaders.

Initially non-functional: Have an independent test for whether to obey
precision qualifiers other than whether the profile is es.

Fix previous commit to not use tabs and otherwise match local coding
conventions better.

HLSL: Better error message for when HLSL translation fails

HLSL: Support string literals, e.g, for annotations

SPV: Some group invocation operations should be applied to scalars.

Use the new function selector for #version 400 and above,
parameterized for the GLSL #version 400 selection rules.

This can be used for both GLSL and HLSL, and other languages
as well.

HLSL and standalone, modifying Standalone to send filename as string source, and HLSL backend will use this to print a better error mesage when things fail

This includes all "per variable" layout qualifiers, but the
key ones mattering and tested for now are:
  set=
  binding=
  constant_id=
  push_constant

SPIRV remapper: allow 64 bit literals in OperandVariableLiteralI…

HLSL: changing SPIRV defualt language for HLSL to unknown

fix x64 warning about conversion size_t -> int

Revert "Merge pull request #456 from steve-lunarg/remapper-literal64"

This reverts commit ad08b30f, reversing
changes made to 28660bb5.

This backs out the pull request
https://github.com/KhronosGroup/glslang/pull/456 because it introduced
several internal errors even on code that only uses 32-bit numeric
types.

SPIRV: Remapper: allow 64 bit literals in OperandVariableLiteralId iteration

Allowing explicit specification of shader compiltion type via -T opti…

Build: Bump required CMake version down to 2.8.11

HLSL: Put all intrinsics in common stage symbol table

Fixes issue #370 and replaces PR #371.

HLSL: add implicit promotions for assignments and function returns.