Improve serial port speed

[malkavi]

I have tried rxtx and purejavacomm in differents projects and in my opinion purejavacomm is faster than rxtx opening ports.
https://github.com/nyholku/purejavacomm
Maybe it can be a good alternative. The change from rxtx to purejavacomm is fast an easy.

Sorry for my english and thanks for the proyect!