Peter M. Groen / openbr

Check for a NULL transform in CacheTransform::init
How can you doubt me?

Conflicts:
	openbr/plugins/meta.cpp

Update multi-threading model used by stream, and some gui tweaks

Also, add FPSCalc, and FPSSynch to calculate the frequency of frames passing
through a stream, and to slow down processing to a specific frame rate (note:
does not work particularly well), respecively.

Rather than having threads at each stage block, and wait for input, use the
global thread pool to only execute stages when they have input.