BUG: incorrect order for output scaling (transformPoints, ...)

Noticed while working on #2565 (closed), the output write scaling should be applied after undoing the effects of the specified rotation centre. Currently the scaling applied before undoing the rotation centre, which means the resulting output would be entirely wrong if rotation centre and output scaling are combined!

assigned to @mark

closed via commit b6a6e40c

mentioned in commit 06a60286

mentioned in commit a72ae125

mentioned in commit b6a6e40c

mentioned in commit 546e2c02

mentioned in commit 53e91f12

mentioned in commit 74ff53cd