New option `-g` to respect Markdown conventions:
1. '##' style headers (new), 2. definition lists (as before), 3. fenced code blocks (as before). NOTE that 2. and 3. are now *require* the `-g` option set, but were formerly by default.
Authored by: tin-pot 2014-02-09
Parent: [r10]
Child: [r12]
