Changed adding Resource and Package files to be able to specify the location in the Vector for search priority when calling GetFile or GetResource
Added the ability to specify whether to search Package Files or Resource Dirs first when calling GetFile or GetResource
Added the functionality to angelscript and lua. Lua does not contain the ability to add resource dirs and packages, so that was not modified.
Skip documentation update if CI build is invoked not on master branch.

Also:
- Setup doxygen configuration on the fly to use minimal theme and to produce SVG instead of PNG.
- Change how the GH_TOKEN is supplied as the GIT version in Travis VM (Ubuntu) does not seem to read the credentials from file store correctly.
- Only generate site documentation after the CI build test has passed.
- Add Ubuntu PPA to install a more recent version of Doxygen.
Move header & footer html template to urho.github.io.

Only do rsync when make doc is successful.
Update assimp to newest revision from git.
Add material emissive color in LitSolid shader also when not using emissive map. Default material emissive color back to zero.
Merge remote-tracking branch 'remotes/alexparlett/resource_search_priority'
Merge remote-tracking branch 'remotes/jtippets/master'
Convert tabs to spaces.
Fix MoveAlongSurface for VS2008.
Exposed missing scene binary load/save & node instantiation to Lua. To use instantiation, call eg. scene:InstantiateXML(fileSystem:GetProgramDir().."Data/Objects/Ninja.xml", Vector3(0, 0, 0), Quaternion());
Import material emissive color & texture in AssetImporter.
Call SetProcessDPIAware() function on SDL video initialization to prevent Windows 8.1 from scaling & blurring the window on high DPI settings. Closes #83.
Added instructions on how to prefix uniforms in shaders.
Document GLSL sampler to texture unit mapping.
Add abort mechanism to prevent error to bring the site documentation down.
Added option to import non-skinning bones in AssetImporter. Closes #82.
Added case-sensitivity option to String::Contains().