Merge pull request #25 from fkrull/refleaks

Fix some reference leaks.
Fixed reference leaks in callMethod_sync() and getattr().
Test round-trip of PyObjectRef.
Consistent refcounting behaviour when converting object references.
Converter: Only use PyObjectRef, add tests

The converter shouldn't need to deal with PyObject * itself, but use
only PyObjectRef, which takes care of reference already.

Make the GIL state management easier to read.

Add a small test that shows how to pass Python objects to/from QML.
Add getattr() and callMethod() tests to test_wrapped
Assignment operator for PyObjectRef + test
Fix deadlock issues and GIL state handling
Bump API version to 1.4, update documentation
Merge branch 'pyobject-wrapper'
Simplify API (remove callMethod again, merge into call)

callMethod(o, attr, ...) is just a special case of:
call(getattr(o, attr), ...)

Starting with import version 1.4, call() now accepts a
Python callable as alternative to the function name.
Use PyObjectRef's automatic reference counting

Replace most Py_.*REF calls with PyObjectRef's automatic
memory management, with borrowed references.
OpenGL rendering in python.
Removed some unused private members.
Print exceptions in renderer methods.
Recreate renderer when callbacks have been redefined.
Added null-checks for callbacks.
PyGLArea: Pass renderer object instead of function names.
Update PyGLArea when properties have changed.
Improved PyGLArea documentation, added example.