[CM] Expose object_type_name/type-name

[bil at ccrma.Stanford.EDU]

Thanks for the suggestion.  I'm thinking maybe type->string
would be more schemish, or is that bikeshedding?  Also it
can't return the built-in string directly because then someone
could inadvertently clobber s7's error messages.
And there are two ways to handle port type names,
type-name would probably replace class-name, etc.
I just spilled a huge cup of coffee all over my
keyboard, desk, myself, and worst of all the mouse pad.
This may take awhile.