Added support for
m4 (m4) - still used in autoconf, and projects like that
shell (sh) - your basic bash, sh, korn shell
sql (sql) - standard "-- " comment, use " " to include MySQL support
xml (xml,xsd) - XML is not HTML, and comments must go after
preprocessin directive, if present.
Merge pull request #12 from DBCDK/add-m5-sh-xsd-support

Added support for m4, sh, sql, and xml/xsd