Disable "Plugins > LOCI > Update LOCI Plugins" in Fiji
Make the options in the file pattern dialog a little more clear

Now, the user must explicitly choose which of the three pattern
specification methods they wish to use.

Closes #6374.
Don't use a FileStitcher if "Group files..." was unchecked

Fixes #9778.
Do not recommend using "Plugins > LOCI > Update LOCI Plugins" in Fiji
Update screenshot of file grouping window
Fix file stitching bugs exposed by ImageJ plugin updates
Fix potential off-by-one when retrieving checkbox values
Merge pull request #320 from melissalinkert/plugin-options

ImageJ plugin option improvements