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_interface.c

@@ -696,7 +696,7 @@ int BPY_context_member_get(bContext *C, const char *member, bContextDataResult *
 		else      printf("PyContext '%s' not found\n", member);
 	}
 	else {
-		if (G.f & G_DEBUG) {
+		if (G.debug & G_DEBUG_PYTHON) {
 			printf("PyContext '%s' found\n", member);
 		}
 	}