It is reported that the built-in lua function os.remove(path) does
not removes empty directories on windows. To fix this a system.rmdir
function is introduced that calls a native win32 function.
Also common.rm(path, recursively) was added which wraps system.rmdir()
to easily delete an entire folder with all its contents.
If the user manually set the desired scale by calling scale.set(1.60)
the scale_level was not set accordingly which meant that later doing
a Scale:Increase/Decrease command yielded incorrect scale amount.
jgmdev
