Remove old hack to indent verbatim environments, and use new, Norm Walsh
sanctioned hack to indent verbatim environments :-)

Explicitly turn off formatting a <variablelist> as a table, it's still
buggy.

Rename "usen-*" to "en-*", as the usage changed in the underlying
stylesheets. The leader to a <warning> or <caution> should now have
the ":" in the correct position.