What is the most mature and maintained Markdown processor?
$ pandoc --helppandoc [OPTIONS] [FILES]Input formats: native, json, markdown, markdown+lhs, rst, rst+lhs, textile, html, latex, latex+lhsOutput formats: native, json, html, html+lhs, s5, slidy, docbook, opendocument, latex, latex+lhs, context, texinfo, man, markdown, markdown+lhs, plain, rst, rst+lhs, mediawiki, textile, rtf, org, odt, epubOptions: -f FORMAT, -r FORMAT --from=FORMAT, --read=FORMAT -t FORMAT, -w FORMAT --to=FORMAT, --write=FORMAT -s --standalone -o FILENAME --output=FILENAME -p --preserve-tabs --tab-stop=NUMBER --strict --normalize --reference-links -R --parse-raw -S --smart -5 --html5 -m[URL] --latexmathml[=URL], --asciimathml[=URL] --mathml[=URL] --mimetex[=URL] --webtex[=URL] --jsmath[=URL] --mathjax[=URL] --gladtex -i --incremental --offline --xetex --chapters -N --number-sections --listings --section-divs --no-wrap --columns=NUMBER --ascii --email-obfuscation=none|javascript|references --id-prefix=STRING --indented-code-classes=STRING --toc, --table-of-contents --base-header-level=NUMBER --template=FILENAME -V KEY:VALUE --variable=KEY:VALUE -c URL --css=URL -H FILENAME --include-in-header=FILENAME -B FILENAME --include-before-body=FILENAME -A FILENAME --include-after-body=FILENAME -T STRING --title-prefix=STRING --reference-odt=FILENAME --epub-stylesheet=FILENAME --epub-cover-image=FILENAME --epub-metadata=FILENAME -D FORMAT --print-default-template=FORMAT --bibliography=FILENAME --csl=FILENAME --natbib --biblatex --data-dir=DIRECTORY --dump-args --ignore-args -v --version -h --help$ pandoc --versionpandoc 1.8.2Compiled with citeproc support.Compiled with syntax highlighting support for:Actionscript, Ada, Alert, Alert_indent, Ansys, Apache, Asn1, Asp, Awk, Bash, Bibtex, Boo, C, Changelog, Cisco, Cmake, Coffeescript, Coldfusion, Commonlisp, Cpp, Cs, Css, Cue, D, Desktop, Diff, Djangotemplate, Doxygen, Doxygenlua, Dtd, Eiffel, Email, Erlang, Fortran, Fsharp, Fstab, Gap, Gdb, Gettext, Gnuassembler, Go, Haskell, Haxe, Html, Idl, Ilerpg, Ini, Java, Javadoc, Javascript, Json, Jsp, Latex, Lex, LiterateHaskell, Lua, M3u, Makefile, Mandoc, Matlab, Maxima, Mediawiki, Metafont, Mips, Modula2, Modula3, Monobasic, Nasm, Noweb, Objectivec, Objectivecpp, Ocaml, Octave, Pango, Pascal, Perl, Php, Pike, Postscript, Prolog, Python, R, Relaxngcompact, Rhtml, Ruby, Scala, Scheme, Sci, Sed, Sgml, Sql, SqlMysql, SqlPostgresql, Tcl, Texinfo, Verilog, Vhdl, Winehq, Wml, Xharbour, Xml, Xorg, Xslt, Xul, Yacc, YamlCopyright (C) 2006-2011
I've been using python with http://www.freewisdom.org/projects/python-markdown/ without any problem so far, and it has a simple extension mechanism.