assume pansn-spec in wfmash parameters to enfoce lower-triangular mapping

[subwaystation]

Description of feature

Mirror pangenome/pggb@1478789.

[subwaystation]

Dependent on #139.

[subwaystation]

Add another parameter that optionally allows the input sequences to not follow the pansn-spec. But then require the user to input the number of haplotypes!

[subwaystation]

Also add a warning, if the input sequences are not in pansn-spec. Make it clear that vg deconstruct will fail for sure.

[subwaystation]

With release 1.1.1 we now apply the lower-triangular mapping. The rest we still need to take care of.