//scale and general region-applied transforms

**Is your feature request related to a problem? Please describe.**
It's difficult to scale a selection in WorldEdit, as `//deform` requires you to select the destination region, not the stuff you want to scale. Additionally, other transforms require you to first copy/cut the stuff to your clipboard, do the transform, and then paste.

**Describe the solution you'd like**
1. `//scale` added, with either `size` or `x,y,z` axes as parameters.
AND
2. Scale should be added in a way consistent with `//rotate` and `//flip`, but all the transform commands as a whole should be able to operate on your selection too, perhaps as `//cmd -s` or similar.

**Describe alternatives you've considered**
See related problem.