vg

Merge remote-tracking branch 'upstream/master'

Merge pull request #4672 from vgteam/vcflib-python

Make vcflib build with default Python for its Python bindings

commented out seqan and abpoa inclusion in Makefile because not being currently used in normalize.

removed inclusion of seqan and abpoa libraries in the normalize cpp code because they are not currently used, and are causing issues because of their outdated compilers.