Fix build on OS X using all external libraries (except xerces)
Add installation command for easier packaging in future
Fix building on Linux using all external libraries (except xerces)
Added more directory to be installed so that the package is more complete.
a sun light can now retrieve the sun position and the turbidity from an environment EDF.
Merge branch 'master' of https://github.com/nyue/appleseed into nyue-master

Conflicts:
	src/appleseed.python/CMakeLists.txt
fixed deployment of files from the Python module on Windows.
added support for Visual Studio 2012 (with AVX code generation enabled).
switched default Windows target from Visual Studio 2010 to Visual Studio 2012.
added support for Visual Studio 2012 to the bundled OpenEXR library.
removed user-specific files from repository.
added support for Visual Studio 2012 to the bundled zlib library.
removed user-specific files from repository.
added support for Visual Studio 2012 to the bundled libpng library.
removed user-specific files from repository.
removed user-specific files from repository.
added support for Visual Studio 2012 to the bundled Xerces-C library.
fixed warnings in the Python bindings on Windows with Visual Studio 2012 x64.
wrap <boost/python.hpp> into foundation/platform/python.h because boost.python generates warnings on Windows with Visual Studio 2012 x64.
added a note about Visual Studio 2012 x64 crashing on exit in Debug mode in certain circumstances (known bug in VS).
added missing #include statement and fixed minor styling issues.