Water/Land/other mask required as parameter in mesher

[NicWayand]

Add to mesher:

Land/water parameter. That way certain modules can be constrained to only run over particular types (i.e. no snow module over oceans (without ice)), or lake/glacier modules only running over those triangle types.)

[Chrismarsh]

resolved in a58e9f1

config files now need a true/false if they want to take advantage

      {
        "desc":"lake",
        "is_water":true
      },