omegat: init at 4.1.5.2

OmegaT is a Computer-Assisted Translation tool written in Java.
This derivation doesn't build it from source, but rather downloads
a 'Cross-platform without JRE' zip file.
I took the liberty of shorting the upstream version naming of
"4.1.5 update 2 Beta" to a more concise "4.1.5.2".