- On/off switches for both hard-wired regions and region files through namelist, like Water Mass Census.
- Replaced single region scratch variable for mask with a variable 'surfaceMask' which stores the mask for all regions.
- Compute the surfaceMask in init step to avoid recomputing it multiple times (similar to what @vanroekel has done for Layer Volume Weighted Averages).
- Minimized range of loops to reduce redundant computations.

I noticed the typo in this variable and when I wanted to fix it, it turned out that it's not used anywhere.
I also added in a comment explaining the 'global' region in the hard-wired mask routine.