racket: ,gcd -> ,pwd

And we display it (the current path, settable via ,cd) as a string.
This was, i'm sure, a secret command nobody is using!
racket: indentation for module*
racket: handling correctly submodules in load handler during ,enter

That is, complying to the submodule loading protocol (cf. racket's own
enter!).
racket: module* and module+ denote submodules too

Recognizing those forms in the elisp module getter.
racket: C-u C-c C-z on a submodule enters it