#86 MARKUP_PLUGIN_MAP

[Reini Urban]

New optional InlineParser + BlockParser mapping from
simple xml as in mediawiki, to the syntax.

Sample:
MARKUP_PLUGIN_MAP = "toc:CreateToc amath:AsciiMath
table:RichTable dot:GraphViz"

<xml argpairs="">body</xml> | <xml>
=> </xml>

Those new xml tags are then extempt from the usual
as-is rule.