Bump mapserver_mod from `ad4e151` to `b4ffb0a`

Bumps mapserver_mod from ad4e151 to b4ffb0a.

Commits

• b4ffb0a chatcommand usage update
• 9b50b06 refactor for after_place_node instead of on_construct, [NOT TESTED]
• d533505 fix luacheck error: pos variable overshadowing
• c6decfc remember last train marker settings per player, also remember color
• See full diff in compare view