As WML evolves, some new features appear and some input files requires
new version to be processed. This include file provides the
"<require>" tag, which checks whether running WML program is
new enough to process input file.
The "<require>" tag takes an argument : the WML version number
needed to process the file in which this tag appears. This number is a
dot separated list of 3 numbers, from left to right : version, revision
Comparison between numbers is numerical, so that 1.7.50 > 1.7.6