fix alphanumericp (lp#1377712)

also write tests for standard-chars for other case-related functions
trivial improvement to char-{up,down}case

only look up the replacement if the source character is of the
relevant case
whoops!  The perfect hash function for case conversion...

... not so perfect
make the chararacter-case lookup be on an array

not a hash-table: we effectively have our own perfect hashing
function anyway.
remove stray evidence of incremental coding

(one #+nil'led out form from a previous iteration).  Also remove
now-unused sorted-position function.