move debug flag into its own global var (G.debug), split up debug options.

--debug
  --debug-ffmpeg
  --debug-python
  --debug-events
  --debug-wm

This makes debug output easier to read - event debug prints would flood output too much before.

For convenience:
  --debug-all turns all debug flags on (works as --debug did before).

also removed some redundant whitespace in debug prints and prefix some prints with __func__ to give some context.

source/blender/python/intern/bpy_rna_array.c

@@ -664,7 +664,7 @@ PyObject *pyrna_py_from_array_index(BPy_PropertyArrayRNA *self, PointerRNA *ptr,
 	len = RNA_property_multi_array_length(ptr, prop, arraydim);
 	if (index >= len || index < 0) {
 		/* this shouldn't happen because higher level funcs must check for invalid index */
-		if (G.f & G_DEBUG) printf("pyrna_py_from_array_index: invalid index %d for array with length=%d\n", index, len);
+		if (G.debug & G_DEBUG_PYTHON) printf("pyrna_py_from_array_index: invalid index %d for array with length=%d\n", index, len);
 
 		PyErr_SetString(PyExc_IndexError, "out of range");
 		return NULL;