Input GUI v2: input image handling

[chalkie666]

This list is just a start - this issue can hold a discussion about what the future looks like for a fully imageJ2 implementation of the Coloc_2 Input user input interface "Input GUI v2" and what it should be able to do.

1. allow selection of images that are already opened by imageJ2 via eg bioformats or scifio an in memory as imglib2 objects
2. allow selection of image files on disk with out necessarily displaying them (perhaps displaying them anyway not a big problem). Drag and drop support?
3. Allow 2 data channel selection from a multi channel image
4. Allow a mask image channel selection from a different image file or the same image file as the 2 image data channels.
5. Set optional analysis methods/displays on or off.

[chalkie666]

one benefit here is to get rid of IJ1 -> IJ2/imglib2 data object conversion complexity and problems,
another is to remove uses of IJ.anything an replace with the imageJ2 equivalent, for eg selecting open images, writing to the log or to status messages in the IJ2 tool bar etc.

[chalkie666]

6. Deal with time series data by processing each time point separately (perhaps in a different thread), then collating the results into a single time series compatible results handler (perhaps with a summary/plot over time)