Finer control over image size needed

[Phergus]

Is your feature request related to a problem? Please describe.
When using the mouse-wheel to resize the portrait image the steps can be too large making it difficult to get just the right size.

Describe the solution you'd like
Would like a way to make the size jumps smaller by perhaps using Ctrl-Mouse-Wheel to produce smaller steps.

Additional context
Original posted on forums by EvilNerf.

[JamzTheMan]

For next release: Control + Mousewheel now reduces zoom (and Control + Shift + Mousewheel for rotation) by a factor of 10 for finer control.

Edit: corrected typo

[Phergus]

Tested.