Make use of molecule information in LinkFragments

[pontushojer]

LinkFragments in the Hapcut2 package is a python script that connects heterozygous variants based on barcode (BX) information. The way it currently does this is by connecting reads with the same BX tag that are within a certain window. This effectively re-calls the molecules we defined in buildmolecules which is quite unnecessary.

Merged PR in HapCUT2 vibansal/HapCUT2#114 to add this functionality. Once the next HapCUT2 version is released we can update the hapcut2_linkfragments rule to use MI tags.

Issue copied from FrickTobias/BLR#212