For characters outside ASCII:
1. repr is wrong in REPL
2. sharp constant #\<codepoint> fails to evaluate
3. sharp constant hex #\x<hexdigits> accepts invalid UTF-8 codepoints
4. a call to error with such a character eats the output string
Also, changed the repr of ASCII control characters (was #\x7)
to their unicode repr (now a box glyph with hex)
Test framework and tests in Scheme, and portable.
Work in progress. Expect commits for more tests.
Testing framework is stable, more or less.
Add more tests
Add tests layer and layerMask.
test Item methods
More tests, selection
Test memory, vector in TS.
More tests char functions
sharp expr tests
