More functionality in the Flagged alignment wizard

[Nicklas Nordborg]

See #1046. It is currently a read-only wizard that can be used for investigations. It needs more functionality:

• We need to add support for scheduling re-extractions, etc.
• When a problem has been "solved" we need to be able to remove items from the "Flagged alignments" list. Items that are contaminated or a mixup need to be flagged or handled in some way (not yet decided). Items that are ok should be unflagged and be uses as if nothing had happened.
• ... and possible more ...