add --sample-prefix to relate

prep for release

remove message

update changes

Add groups (brentp#29)

* start of fix for brentp#26

* adjust ab cutoff

* finalize test

* add tests to nimble

* increase proportion other and update changes

* support for GVCF (brentp#27)

* docs and spelling

update changes

set default output dir

add arraymancer to deps

better error messages and better findsites

fix/work-around for brentp#15