Tools.Markdown: Improved support for old PCRE.
Adds workaround for versions of PCRE that don't support havinf the end
marked in character classes.
Fixes testsuite failure on Fedora Core 4.
Tools.Markdown: Escape # in Regexp.PCRE.Widestring patterns.
Unescaped # introduces a comment if the PCRE library has been
compiled with the PCRE_EXTENDED option set.
Potential fix for testsuite failure on Fedora Core 4 (pcre 5.0-4.1-fc4).
Tools.Markdown: Protected lfuns.
Merge remote-tracking branch 'origin/master' into new_utf8
Merge remote-tracking branch 'origin/8.1' into gobject-introspection
Tools.Markdown: Fixed requirement check.
Tools.Markdown: fixed warning
Move Markdown code to Tools, as it is more of a tool than a module.