Modified Cell Counter plugin for ImageJ -- Stack Counter

[David Eccles (gringer)]

Hello,

I've updated the Cell Counter plugin for ImageJ to fix a few bugs, and
included a few features suggested by a researcher in my institute, as a new
plugin, 'Stack Counter'. I have renamed all the classes, so it should work
beside 'Cell Counter' even though it does (almost) everything that 'Cell
Counter' can do.

A summary of changes can be found here:
http://user.interface.org.nz/~gringer/hacking/stack-counter.html

The ImageJ plugin can be found here:
http://user.interface.org.nz/~gringer/hacking/download/jars/stack_counter.jar

Please note: this is my first experience with plugins for ImageJ, so I may
have coded things in the wrong way for full support / functionality.

David