Consistent checks for the 'dots' and 'mask' parameters in VizEquiMap.R

Hi,

This issue is to report an inconsistency in the checks for the dots and mask parameters in VizEquiMap.R. The newer checks for mask are based on VizRobinson.R's mask checks, but the mask in VizEquiMap.R has a similar structure to the dots parameter, not the mask in VizRobinson.R (see !25 (merged)). It may be worth harmonizing these checks for consistency.

Best regards,

Ariadna