Add missing keywords, fix disappearing units.

https://bugs.eressea.de/view.php?id=2051
. The orders PASSWORT, FAHRE, KÄMPFE were not recognized (new imperative syntax).
. Added backwards compatibility for FIGHT (now COMBAT).

https://bugs.eressea.de/view.php?id=2050
. units were always giving away ALL persons, not the number in their GIVE command.