Opening a cuesheet adds it to the current cuesheet #520
Description
Describe the bug
Having a cuesheet opened and opening another cuesheet just adds the tracks to the current cuesheet.
To Reproduce
Steps to reproduce the behavior:
- Have a cuesheet with tracks
- Click on 'File' -> 'Open' and open a local cuesheet file
- See the tracks beeing attached
Expected behavior
If there are unsaved changes, I would assume to have a dialog asking if I really want to import the cuesheet. If I click yes, the current cuesheet should be overwritten by the import. The same question should come up when opening an project file.