SAFE-SIMPLE-READ-FROM-STRING may now make symbols if told so

* common.lisp (uri-to-arguments): Don't resignal if *CATCH-ERRORS*
is nil. Fix indent.
(read-for-resource): Don't check for errors here and pass t to
SNOOZE-SAFE-SIMPLE-READ:SAFE-SIMPLE-READ-FROM-STRING.

* safe-simple-read.lisp (parse-symbol): Return 4 values.
(safe-simple-read-from-string): Take MAKE-SYMBOL-P. Update
docstring.

* snooze-tests.lisp (test-some-routes): Update test.
(safe-simple-read-should-error): Update tests.
(safe-simple-dont-read-back): Delete this test.