Remove map specific attributes from the listing.

People that want map attribute information can run the relevant
s2gs files through and get proper mappings for their use case.
Raise an informative error on corrupt tracker file

This way people can reliably catch this issue and deal with it as
they wish.
Fix python3 bug in plugin error handling routine.
Fixes #160 with non back compatible changes.

Renames all ability events as following:

* AbilityEvent -> CommandEvent
* AbilityEvent -> BasicCommandEvent
* TargetAbilityEvent -> TargetUnitCommandEvent
* LocationAbilityEvent -> TargetPointCommandEvent

As such, all references to these classes, statements that check the event name,
and engine plugin event handlers need to be renamed. Its not ideal but it is
much better than being wrong.
Remove some old % style string formatting.
And this is why you run tests before pushing.

refs #160
Make note of the additional changes in the log.
Merge remote-tracking branch 'upstream/master'