Refactor out callbacks into echo module
WIP Line profile viewer
Profile object picking
Spectrum mouse mode
Callback property decorator
WIP Spectrum tool
Spectrum Viewer Handle deactivated on mouse modes
Spectrum selector scrubbing
Make some image client properties callback-able
Mouse modes can be disabled
Cleanup spectrum tool code
Anchor Spectrum tool below image widget
Cube slices default to center of cube
Tidy up Spectrum icon
Fix display of image subsets in rotated slices
Double click to center spectrum slice
Profile fitter, spectrum tool context panel
Rename Handles to Grips
Plot fit residuals
Catch some profile edge cases