soc-2008-mxcurioni: added Iterator class, base class for all iterators in Freestyle (on the C++ side). Created the equivalent in Python BPy_Iterator with the simple interface:

- getExactTypeName()
- increment()
- decrement()
- isBegin()
- isEnd()

Contrary to previously stated, I am reverting back to implementing iterators in the (Python) API, for different reasons:
- it will make testing quicker to achieve, as I won't have to recode a big chunk of the original Python files
- it will be a base for API refactoring
- it won't prevent the use a list-based approach later (it is simple to get it from the Iterator)

source/blender/freestyle/intern/python/BPy_Freestyle.cpp

@@ -5,6 +5,7 @@
 #include "BPy_Id.h"
 #include "BPy_IntegrationType.h"
 #include "BPy_Interface0D.h"
+#include "BPy_Iterator.h"
 #include "Interface0D/BPy_CurvePoint.h"
 #include "BPy_Interface1D.h"
 #include "BPy_MediumType.h"
@@ -142,6 +143,7 @@ PyObject *Freestyle_Init( void )
 	IntegrationType_Init( module );
 	Interface0D_Init( module );
 	Interface1D_Init( module );
+	Iterator_Init( module );
 	StrokeAttribute_Init( module );
 	StrokeShader_Init( module );
 	UnaryFunction0D_Init( module );