tr: support [:xdigit:], fix handling of ranges and [x]'s.
 add testsuite entry for each of 3 bugs fixed.

function                                             old     new   delta      
static.classes                                        73      82      +9      
expand                                              1738    1743      +5      
complement                                            74      72      -2      
tr_main                                              472     463      -9      
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(add/remove: 0/0 grow/shrink: 2/2 up/down: 14/-11)              Total: 3 bytes

2 files changed