Unit groups

Giving commands one by one to huge numbers of ships is not very handy, not to mention all other problems like small ships getting lost in some corners of space. So I added some group controls to the combat UI. Now ships can form groups, like in many RTS-games, and there is also a button to choose all remaining ships. Groups can be selected by pushing the corresponding numeric button or by clicking near the midpoint of the group. I still keep the option of choosing ships freely, but I might change it later so that the groups are fixed like in Total War -games. That might be a much easier way to command the armies and probably wouldn’t restrict the combat too much. But will have to test and see if that is needed.

Also added a button which shows the command queue of all ship groups.