add probabalistic filters
add test for sampling
Merge pull request #401 from Garonenur/dw

this PR adds some filters to the seqfilter tool
fix double free bug

Addresses #340.
Merge pull request #402 from satta/segfault

fix double free bug
comments on obscure ref/del cycle
typos
complete documentation of new Lua node API
update documentation
Merge pull request #403 from satta/cosmetics

Cosmetics and documentation
do not use -m64 for arm64

Incorporates patch from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=748708
Merge pull request #404 from satta/aarch64

do not use -m64 for arm64
make sure we only translate sequence of at least one codon length
add feature_node:appears_as_root_node, many fixes
add some helper functions to speclib
extend example spec with more detailed cases
Merge pull request #405 from satta/speckwork

Many fixes and additions to spec checker
pre-cache seqids for -matchdescstart optimization

Closes #363.
overflow prevention
cosmetics