Allow removing multiple units through the ECS
Merge develop to avoid conflict
Test fixed after merge.
Added comments about removing pending units

Fixed test.
Merge pull request #493 from makyo/del-units

Allow removing multiple units through the ECS

The Remove Units call allows removing multiple units by passing an array to be removed.  The ECS was not taking this into account, and now does.

Note: there currently isn't a way to remove ghost units in the UI.  This functionality is tested with a unit test, however, and that work passes.