Slurry and Fertilizer Trailer

This is an edit of the default water trailer to load slurry and fertilizer from the default triggers.

Because it uses default specializations it will generate two errors;
1) in the [F1] HUD saying to turn on the trailer and
2) in your log file saying that no spray usage is specified.

These in no way affect game performance but are just a function of the default scripts not being used as intended...

You can use this to load excess slurry and sell it at a sell point, as well as load fertilizer from a default trigger, dump it on the ground and then using a suitable loader that accepts fertilizer, load it into a trailer or spreader that allows filling from the air.

The trailer no longer accepts water as a fruit type...