more informative /npc call <tag> command output

updated /npc help

- /npc call <tag> command added to call in NPC mercenaries
- config options to enable/disable the system and define mercenary SC and reputation costs

wrongly named GPS Mission Waypoint from /npc mission show gps command renamed to Enemy Position.

updated help command

new command /npc mission show gps , which shows the position of closest mission enemy ship/station

language resources are now being loaded by the Translation Script mod

mission code cleanup

- tweaked target prediction code
- tweaked gyro override code (NPC ship turning)