#197 Rewrite UI using model/view separation

This is a draft of MR and allows to follow the progress on rewriting with model/view separation.

At the moment, measurement types are done and I am working on gels table. Then will move towards the next ones. It looks to me that it is the way to go and relatively simple as I can reuse the solutions for corner cases that you have found already.

• Add API for row that can be selected by clicking on a cell (gel table). See if we should do it by tracking single mouse click on view side
• Allow to select item by keyboard, set selection to the cell used for selecting the item for future keyboard navigation
• Add API for stretchable columns
• Replace position of reference/success and comment columns
• Add measurement table
• Link gel model and list of buttons on the left. Moved out of this MR to issue #203 (closed)
• Add gel images view and list

Was suggesting to remove toolbar "New ..." buttons, but maybe they should stay. As well as adding new ones for Delete and connecting them with the corresponding models. But that should probably be separate issue

Finally, after review

• Remove old tables and corresponding UI elements
• Open an issue regarding toolbar and its connection to models. Opened at #209 (closed)
• Open an issue: new lanes button is still enabled even if all gel lanes have been added to the image

Fixes: #197 (closed)