Update es_ES.po

Left some acronyms (SAC, CNS, EADD, MOD ...) untouched because I think
they are used mainly this way, specially by technical divers,  while have
translated other like PEA for EAD or PNE for END because they are used
both ways.  There are some others I never heard of in spanish, always in
english, even when talking spanish divers,  like CC Setpoint.

Signed-off-by: Salvador Cuñat <salvador.cunat@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>