Simulated post-editing support in moses and mert-moses.pl

I've been working on improving post-editing support in Moses.  I added an "update" XML tag that works with Ulrich's excellent dynamic phrase table implementation to incorporate new data at runtime.  The script "moses_sim_pe.py" parallelizes simulated post-editing and works with mert-moses.pl.  One catch I noticed is that a thread appears to continuously process XML tags of buffered input sentences rather than waiting for the decoding threads to reach them so there is a danger of sentences' being added to the model before they are translated.  This is easy to fix by wrapping each moses process with a synchronous I/O layer (done in the above script) but is still something to watch out for.  I'll write up some proper directions for using everything soon but now it should be relatively easy to train systems for post-editing using as many CPUs as possible.

Best,
Michael