libhb: thread nlmeans filter
Scales well with number of CPUs, so is 4x faster on quad cores.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6397 b64f7644-9d1e-0410-96f1-a4d463321fa5
WinGui: Fix an issue loading preset Maximum Width/Height info. This was causing previous preset values to be used when calling the libhb calculation logic, leading to bad values.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6398 b64f7644-9d1e-0410-96f1-a4d463321fa5