Copied and pasted _refresh_cb from omero_image.html to preview
Channel btn onCilck refs OME.preview_viewport not 'viewport'
Adding more js and html from omero_image.html to preview
Channel sliders and buttons mostly working in Preview
Update channel buttons on channelChange
Common viewport code into omero_image.js DRY
Moving applyRDCW() to omero_image.js
Move channelChange() to omero_image.js
Update channel checkboxes when toggling channel btns
add SQL for filtering original files by repository
add repository DAO method for filtering files by repository
add API method for setting files' checksum
genericize Executor.Work

would be nice to do in general with Executor but that's a larger job
implement new repository method
test new repository method
Added channel picker to preview panel
Adding link '999' templates to omero_image.html for omero_image.js
Start / end inputs show min / max via tooltips
One row per channel in rdef table
'Save' btn working -> setImageDefaults() in omero_image.js