Uncapitalized the external_id value for Clisp repl

Using the "eval in" and "transfer to" commands with the Clisp repl weren't working for me until I uncapitalized this. After uncapitalizing the external_id and restarting the repl, they worked fine. Switching it back to a capital `Lisp` and restarting the repl broke it again.

This seems to be the problem that we discussed previously on Twitter about the source file's language scope and the external_id of the repl having to match, as seen in https://github.com/wuub/SublimeREPL/blob/master/text_transfer.py#L77

For what it's worth, my file was using the default Lisp syntax mode, and had the extension `.lisp`.