markdown: reports incorrect location when unsupported feature is used

[edwintorok]

$ cat >x.md <<EOF
aaaa
bbbb

dddd

EOF

lambdoc says: The document uses an unsupported feature (Html_comment). and highlights the first line in the source, but the unsupported feature is used on line 4 actually.

[darioteixeira]

This is a know issue: the current version of OMD does not record location information.

[darioteixeira]

The resolution is the same as that of issue #25: Since commit f59a2ae, there is now a Lamblite parser that handles both Markdown and Wiki syntaxes, bypassing OMD altogether, and having proper support for location information.