Danubius bugfixes, refs D380, D371, D204.

Fix broken targetClass parsing as reported by bb on 2017-04-19.

More space between islands and the shoreline as proposed by causative.

Fix typo reported by Sandarac.

Revert the terrible decision to set attackers to violent,
which caused siege engines to change the target from the civic center to the units that attacked it and
ships to become stuck at the shoreline more often trying to fight back against unreachable towers.