Added 3delight support to travis build.
Fixed RenderManShader compilation in Clang 3.4.
Skipped RenderMan tests requiring a license in Travis builds.
Merge pull request #1000 from johnhaddon/travisDelight

Travis delight
Updated JH personal build config.
Fixed OSLRenderer for compilation for OSL version 1.5.

This version changed the signatures of many of the virtual methods that RendererServices must implement.
Fixed OSLShader for OSL version 1.5.

OSL 1.5 changes many string fields to ustring - we take advantage of the fact that both have a c_str() method so that we can compile for either version with largely the same code.
Merge pull request #1002 from johnhaddon/osl1.5Compatibility

OSL 1.5 compatibility
Added custom diff support to SceneInspector.

The UI classes now accept a diffCreator argument, which can be passed a callable which will return a subclass of Diff. B

API Incompatibility : SceneInspector.DiffRow() now takes an optional diffCreator argument instead of a compulsory diff argument.
Added set membership section to SceneInspector.

Fixes #930.
Fixed crashes when passing None to PathMatcher python methods.

Boost python will happily extract a NULL pointer from None when asked for any pointer type, so we need to guard against it. In this case we can replace some wrapping functions and allow the implicit ScenePath conversion registered in ScenePlugBinding.cpp to do the work (this was added after the offending code).
Fixed SceneInspector set membership section for invalid paths.
Fixed display of invalid paths in SceneInspector.

Inspectors can't return HTML now, because we escape HTML characters. Also simplified disabling of per-character diffs now we have a proper way of doing it.