Consider removing the --type-set option

[petdance]

I think we might be able to get rid of --type-set option, since it is only used to overwrite a previous definition for a type, and that can be done with --type-del and --type-add.

Thoughts?

[flwyd]

The description of the --type-add flag says "… are recognized as being of (the existing) type TYPE." I interpreted this to mean that, when defining a new type, one must first use --type-set so that it's define, because --type-add only applies to an "existing" type. So if you deprecate the --type-set flag, consider improving the documentation of --type-add.