Draft for Image CRUD with conflicts

[odinkomnogim]

Since mosaic CRUD is not merged, I decided to start parallel work on image CRUD (so it will probably be with conflicts again, but i'll fix it). There are 2 major issues:

1. Your initial script for 'update_images' is quite hard for me to understand. Callback and error handler are the same as function, so:

• I am not able to update image table with callback

• We call this function, probably, to much (?), so It gives an error, saying that 'mosaic_id' argument got multiple values.

  So I tried to implement it differently.

2. When first adding image(s) to mosaic and then clicking on mosaic preview, we get right results. But when I add or delete image in the next iteration, preview stays the same even after plugin or QGIS reloading. Is this the issue with plugin or something else. I suppose tileUrl is not being updated (?), because the list of images is right and their previews work fine.