Added a missing const cast for Python v2.
Fixed the name of the source file of the _json module.
Removed a stray semi-colon.
Scopes are handled properly in the source and include path of required
additional libraries.
Exclude cython and c-extension files.
Add missing _scproxy dependency on Mac OS X.
Add missing sysconfig package.
Add support for extension modules.

While pyqtdeploy does not attempt to automatically resolve dependencies,
it should still support loading of extension modules manually put in right directories.
Current implementation looks for extension modules named after their fqmn
next to the executable. In addition the PlugIns and Frameworks directories are checked
on Mac OS X.