v1.2 gains benchmarking, improves mirroring and testing

With this release, demicode gains the ability to benchmark page rendering. Initial results for nine terminal applications suggest that all of them are reasonably fast at rendering styled text, taking 4–9ms for a 120×40 page on a four-year-old macOS laptop. But when demicode queries the terminal for the current column (once each for 38 of those 40 lines), the spread of average latencies explodes to 10-946ms. Judging by these results, it seems that a few terminals strongly oversell their nimbleness.

This release also improves the mirroring of UCD and CLDR data, introducing a from the ground rewrite that uses an explicit manifest to track what data has been mirrored. To see for yourself, --ucd-list-versions lists the UCD versions included in the current mirror. The implementation also is more structured and performs more aggressive error checking. As of today, demicode is using GitHub actions for CI, which hopefully ensures that demicode releases become only more robust.