editbone.transform(matrix) function, requested by Cessen.

Also added matrix.median_scale attribute to get the average scale from the matrix, use for scaling bone envalopes.

source/blender/python/generic/vector.c

@@ -1421,7 +1421,7 @@ static PyGetSetDef Vector_getseters[] = {
 	 (getter)BaseMathObject_getWrapped, (setter)NULL,
 	 "True when this wraps blenders internal data",
 	 NULL},
-	{"__owner__",
+	{"_owner",
 	 (getter)BaseMathObject_getOwner, (setter)NULL,
 	 "Read only owner for vectors that depend on another object",
 	 NULL},