any qstr of >= 3 chars long is a candidate for use; the input byte value
(1) is used to indicate a fixed-length qstr number follows.
Before accounting for the code size changes, this saves ~100 bytes
on trinket m0, but it may end up being a wash due to added code.
A cutoff of length>2 is slightly better for ja and ru and worse for others.
This has to do with the relative frequency of latin characters vs non-latin
characters, is my guess.
lang after before change (- = more free space)
en_US 3132 2996 -134
fr 2136 2060 -76
ja 1916 1724 -232
ru 2196 2000 -196
4d8b354c13