Python Mapscript's SetLayerDrawingOrder/GetLayerDrawing typemap

[dstrevinas]

Currently those functions need a typemap between SWIG pointers to the integer array and a python integer tuple. Observing pyextend.i which contains some extensions to the python mapObj, there currently exist two functions doing exactly the same thing while using the correct conversions to the PyObjects:

PyObject *getLayerOrder()

int setLayerOrder(PyObject *order)

I propose that they are renamed getLayersDrawingOrder and setLayersDrawingOrder respectively to agree with the documentation. An addition should be to check if setLayersDrawingOrder's python tuple argument contains integer values and return the appropriate exception string. I have attached a working version of setLayersDrawingOrder.