Do image resizing using multiple threads
Do image resizing using multiple threads

In my (non-scientific) testing on my 2-core development machine,
resizing went from 12.5 seconds when single-threaded, to 8.8 seconds
when multi-threaded. Of course, as usual YMMV.

Karmabunny/resiz-o-tron,Karmabunny/resiz-o-tron