The data operand editor determines low vs. high ASCII formatting by
examining the first byte of string data. Unfortunately the test was
broken, and for strings with a 1- or 2-byte length, was testing the
length byte instead of the character data. This is now fixed.
This also changes the way empty strings are handled. Before, they
were allowed but not counted, so you couldn't create an empty string
by itself, but could do it if it were part of a larger group. This
was unnecessarily restrictive. Empty L1/L2/null-term strings are now
allowed.
This means that a buffer full of $00 can be formatted as a big pile
of empty strings, which seems a bit ridiculous but there's no good
reason to obstruct it.
(issue #110)
