Do not report on or try to interpret when all alts are failed
stop calling _load more than once
Make factory a package global in plan base class
use get_class instead of _load
Change way that BamReadcount::Entry en(de)codes for vcf
Make decode and encode even faster
Avoid is_many lookups (they're very slow)
Use differ instead of compare_ok
Don't memoize something that is only called once