digraphs: add proposals for rare latin smallcaps forms

Just add all small capitals as far as covered by Unicode, even though
they aren't (to be) used and unsupported in most fonts.  Yet it may
still be expected, and in those cases confusing to only find the common
linguistic range.

If nothing else, allows one to show off Unicode skillz by writing family
names in forced smallcaps (Oɴʟʏ try this at home).