Implement new experiment creation
This merge request implements support for creating new Experiment assets.
It also added automatic selection of the newly created asset.
By implementing that, fixes to both Plotter and Plotterparameters editor have been implemented as the prototype rightfully does not use valid assets.
As a side effect, the handling of "empty" or wrong asset has been improved.
Relevant issue(s) fixed:
Related to #185
Fixes #226 (closed)
Fixes #244 (closed)
Fixes #245 (closed)