Regional capabilities for precip variability

[acordonez]

• [x] Subset grid by latitude and longitude - CropLatLon function and parser updates
• [x] Add "standard" calendar checks
• [x] Update filenames for arbitrary grid size
• [x] Update RegridHoriz function for arbitrary lat/lon resolution
• [x] Update Avg_PS_DomFrq to add custom region option
• [x] Add option to crop dataset via shapefile
• [x] Check for any remaining cdat reference to remove
• [x] Clean up new code
• [x] Resolve conflicts
• [ ] Document new features