Lattice deform

Hi IStonia,

Have made some quick tests on
"Slide", "Lathe" and "Spline Modify" with scale/scale lock on worldspace/workplane space, even with workplane space origin in some strange locations / orientations, to see outcome, and all OK.

Orthographic views on workplane space now appear to work as expected, without problems of change of view on zooming in/out.

So up to now, all looking very good.

I will spend some more time testing, just to see if I have missed any problems (and have some fun experimenting).

Many thanks for taking the time to implement this.