Account for quittingViaMacro in ImageJ 1.49q5

[hinerm]

See http://fiji.sc/bugzilla/show_bug.cgi?id=1022

ImageJ 1.49q5 will add a quittingViaMacro method which bypasses the save dialog for dirty images when quit is called in a macro.

We will want to handle this similarly to the general quitting mechanism, whereby we either iterate over all windows manually to close them, or consider disabling this flag.

[hinerm]

Note that we need to be careful not to be overly aggressive, as if a dirty image is closed during a macro it shouldn't pop a save dialog...

The goal of this issue is just to ensure things are all shut down appropriately.