The lexer mishandled cases like "#x1E+2", because "E" is
not an exponent marker for hexadecimal --- and it has been that
way forever, but the repair isn't all that difficult.
and change the tests so they all run with port line
counting enabled (or else the unicode test fails)
adjust module-lexer.rkt tests so they can run in either
port-counting mode or not (but currently run them all in
port-counting mode because scheme-lexer doesn't work without it)
also make a first stab at what needs to change in the module
lexer to make it work in non port line-counting mode
with drdr
also change two of the failing tests so they pass, but incorrectly and
add a note there to that effect so if someone does fix that eventually
they won't be confused (I hope)
