Resolve "saving-trc-files-after-opening-a-new-project "

Make name of last trajectory file exported member

• Move from static var to member var so it can be changed from other methods
• Reset it when loading in a new project

I also added setter/getter for usage in !154 (merged)

Closes #259 (closed)

added Doing label

Should the default export name be set to project.trc? For me it remains empty when exporting for the first time, and also after changing the project. Afterwards everything is set as expected.

resolved all threads

approved this merge request

merged

mentioned in commit d34d9788