tomo: Display detector data on top of the tiling view
This PR allow to display the active detector data on top of the tiling view.
For now
- Only the data with flatfield correction is display
- The data can be displayed or not
- It can be configured with few parameters like lut/norm/autoscale
- Fixed refresh rate (1 second server side, 0.5 second client side)
It's a first step. But which already can be merged.