For "s.m = t", a sampler member assigned a sampler, make t an alias
for s.m, and when s.m is flattened, it will flatten to the alias t.
Normally, assignments to samplers are disallowed.

This avoids either A) needing uniformConstant struct, or
B) initializing a struct with opaque members, as writing them is not
allowed.

Because it is valid in HLSL to alias bindings:
A) remove validation that aliasing is not done
B) make the algorithms tolerate aliasing

HLSL: Add an Includer to handle #include for local HLSL paths.

Parser: Add missing codes for float16

SPV: Add OpSource shader source code and file name.

Note that declaratives are not handled, only procedurals.

Pure Texture to Sampled Texture Transform

Adds a transformation step to the post processing step.
Two modes are available:
1) keep
- Keeps samplers, textures and sampled textures as is
2) transform pure texture into sampled texture and remove pure samplers
- removes all pure samplers
- transforms all pure textures into its sampled counter part

Change-Id: If54972e8052961db66c23f4b7e719d363cf6edbd

HLSL: Add imat, umat, and bmat constructors

Fixes #894

Blocks have this on members, not the object.

HLSL: allow name mangling based on texture template type

This was done for one direction, but not both directions, so this commit
picks up the other direction.

This seems a bit ill-defined, and was generating code that made OpPhi of two
operands that were Boolean vectors result in a scalar bool.

Name mangling did not account for the vector size in the template type of a texture.
This adds that.  The mangle is as it ever was for the vec4 case, which leaves
all GLSL behavior and most HLSL behavior uneffected.  For vec1-3 the size is added
to the mangle.

Current limitation: textures cannot presently be templatized on structured types,
so this works only for vectors of basic types.

Fixes #895.

SPV: Give error on not assigning locations to I/O when generating SPIR-V.

Remapper: handle embedded opcode in OpSpecConstantOp

OpSpecConstantOp contains an embedded opcode which is given as a literal
argument to the OpSpecConstantOp.  The subsequent arguments are as the
embedded op would expect, which may be a mixture of IDs and literals.  This
adds support for that to the remapper binary parser.  Upon seeing such an
embedded op, the parser flips over to parsing the argument list as
appropriate for that opcode.

Fixes #882.

Also, provides an option to auto-assign locations.
Existing tests use this option, to avoid the error message,
however, it is not fully implemented yet.

HLSL: add ability to pass struct buffers with counters to fns

HLSL: Implement member functions calling member functions.

Fixes #883.

This modifies function parameter passing to pass the counter
buffer associated with a struct buffer to a function as a
hidden parameter.  Similarly function declarations will have
hidden parameters added to accept the associated counter buffers.

There is a limitation: if a SB type may or may not have an associated
counter, passing it as a function parameter will assume that it does, and
the counter will appear in the linkage whether or not there is a counter
method used on the object.

track declared builtin type

Marking as WIP since it might deserve discussion or at least explicit consideration.

During type sanitization, the TQualifier's TBuiltInVariable type is lost.  However,
sometimes it's needed downstream.  There were already two methods in use to track
it through to places it was needed: one in the TParameter, and one in a map in the
HlslParseContext used for structured buffers.

The latter was going to be insufficient when SB types with counters are passed to
user functions, and it's proving awkward to track the data to where it's needed.
This PR holds a proposal: track the original declared builtin type in the TType,
so it's trivially available where needed.

This lets the other two mechanisms be removed (and they are in this PR).  There's a
side benefit of not losing certain types of information before the reflection interface.

This PR is only that proposal, so it changes no test results.  If it's acceptable,
I'll use it for the last piece of SB counter functionality.

HLSL: add .mips[][] operator for texture types

This implements mytex.mips[mip][coord] for texture types.  There is
some error testing, but not comprehensive.  The constructs can be
nested, e.g in this case the inner .mips is parsed before the completion
of the outer [][] operator.

   tx.mips[tx.mips[a][b].x][c]

Check Android build on Travis CI

Also stop requiring sudo privilege so that we can use containers
for testing.

HLSL: allow GS-specific methods in non-GS stages