chore: revert building rules

This puts our repo in a "dirty" state, which makes `make compare` and
GoReleaser fail.

chore: fix Go versions

fix: remove ineffectual assignment to `recur`

docs: remove note

perf: compile filters

feat: detect front matter delimited by `+++`

chore: drop Travis CI caching

chore: add `brew` to GoReleaser

chore: update .gitignore

chore: fix AppVeyor