Added a UnitZoneChange event that is fired whenever a unit's zone membership changes.
The unitsInZone output variable is now updated based on UnitZoneChange events.
The unitDaysInZone and animalDaysInZone output variables are now updated based on UnitZoneChange and Destruction events.
Merge branch 'master' into simpler-reporting
Merge branch 'master' into simpler-reporting
Simplification: removed the MPI compile option (issue https://github.com/NAVADMC/SpreadModel/issues/238).
Some more small gitignore items for compiling
graceful_startup() including fallback call in edit_entry that doesn't seem to work well.  #237
Fixed 2 places where MPI still appeared in a Makefile.
new_entry fallback to graceful_startup() working as intended.  #237
Merge remote-tracking branch 'origin/master'
new_entry fallback to graceful_startup() working as intended.  #237
Recommitting the commit that was reverted by its evil twin.  i.e. Reverting the revert of the previous commit that doesn't look like a revert.  #237
Tests of the convex hull function were failing. Needed to break up long input lines for some tests.
A few more .gitignores for files generated when the test program DejaGnu runs.
Added an update link for #240
Merge remote-tracking branch 'origin/master'
Fixed up some failing tests in the unit/ directory. Failures came from still using the old "herd" terminology.
Update chain is done except that update_status(True) never gets called anywhere.  It should call this once when the program starts. #240
Merge remote-tracking branch 'origin/master'