Changing SceneInterface methods readTags and hasTags with tag filter parameter.

- Added an enum in SceneInterface with bit mask values: LocalTag, DescendentTag and AncestorTag and EveryTag (for convenience).
- Changed the default behaviour of the readTags and hasTags, which would return all tags and now it defaults to LocalTag to be more consistent with the other read functions and because the other tags may not be supported by some implementations of SceneInterface (like MayaScene or HoudiniScene).
- Revisited LinkedScene behaviour and now, tags that are set in the main scene are available as ancestor tags if reading beyound link locations.
- Reviewed and added tests.
Preventing returning true if hasTag was passed zeroed filter.
Replacing Descendent to Descendant to please picky people.
Preventing readTags to raise if filter == 0.
Updating changes for 8.0.0-a23
Added __USE_ISOC99 #define to mac builds.

This is necessary to work around problems with boost/numeric/interval.hpp. Formerly we had been requiring that people building on OS X did this manually, whereas the Gaffer build does it automatically - this brings the two into line.
adding include for gcc 4.4
Fixed IECoreArnold for TBB 4 on OS X.

TBB was including headers which #defined MIN/MAX, which then clashed with the arnold inlines functions of the same name in ai_types.h. The solution is to make sure that ai.h is included before anything else (except boost python, which has its own reasons for wanting to be first).
Merge pull request #164 from johnhaddon/osxPublicBuildFixes

OSX public build fixes
Fixed multiple transform bug in Houdini Scene. Added test case for it. (ticket #4917)
Merge pull request #165 from valeriebernard/houdiniSceneMultipleTransformsFix

Fixed multiple transform bug in Houdini Scene. Added test case.
Added bindings for the WarpOp's FilterType parameter's enum values.
Added the BoundMode parameter to the WarpOp.
The new parameter specifys how out-of-bounds pixels are sampled from the input image. A new option "SetToBlack" has been added which sets pixel samples that are out of bounds to black.
The default value is set to "Clamp" to ensure backwards compatability.
Merge pull request #160 from ldmoser/ancestorTags

Changing SceneInterface methods readTags and hasTags with tag filter parameter.
Updating version and changes
Adding overrideTransform toggle which exposes the t,r,s parms.

This can be used to override animated transformations coming from the file with user specified transforms.
Reorganized SceneCache parms.

Moved Push button and all the options it effects to a new Options tab
Added attributeCopy option parm (used in next commits)
Pushing the attributeCopy parm when expanding SceneCache OBJs
Creating struct for SceneCacheSource parms to avoid function bloat