SBCL's reader changed recently. Fix some issues caused by that.

* swank-source-path-parser.lisp (make-source-recording-readtable):
Wrap the sharp-dot "#." reader before wrapping the dispatch macro
"#" because with the new reader get-dispatch-macro-character
doesn't work if "#" is wrapped first.  Suggested by Paulo Madeira.
(skip-whitespace): New helper.
(read-source-form): Use it.  Skipping over whitespace is a slight
improvement and seems fairly conservative.
* slime-tests.el ([test] find-definition.2-2): New test.