Improve alignment by merging stitching and alignment collections

[arentkievits]

Problem:

• Point match collections for stitching and alignment are currently separate. Alignment does not use stitching results which leads to a bad quality alignment

Fix:

• Merge match collections at alignment step to improve alignment results, as BigFeta can use both stitching and alignment matches to do the fine alignment.

[arentkievits]

Created a single match collection, implemented separate routines to extract point matches from stitching and alignment.