Revisions of general standards

[mpadge]

Points raised by @rkillick in her review of the brolgar package by @njtierney as "not covered but should be":

• Visualizations being appropriate; this should be in the general standards section.
• Mapping some of the specific standards to 1-d input variables onto tabular input. For instance, 1-d input specifies the type should be checked. This should also apply to the type for tabular input (necessarily each column for data frames).

The latter point is one which needs to be addressed in general standards.