TRAMP improvements

[vemv]

• Add a Dockerfile for TRAMP development purposes
  • Includes a README.
• Make TRAMP functionality work when using non-standard ports
  • e.g. when we connect from a SSH port other than 22.
• Don't lose the CIDER session over TRAMP files
  • Makes M-. work recursively (instead of just once) when using TRAMP.
  • Fixes CIDER session is lost when navigating to definition #3250

[bbatsov]

The changes look good overall. Do we also need to update/extend https://docs.cider.mx/cider/basics/up_and_running.html#working-with-remote-hosts ?

[vemv]

Hey @mmontone @igrishaev ,

No linked CIDER sessions should be far more rare to encounter now (as of CIDER master, as released already into MELPA non- Stable)

• For vanilla CIDER connections, it generally shouldn't happen
• For TRAMP connections, we fixed the issue
• For Docker-backed connections, we also fixed the issue

It would be much helpful if you could try removing the workaround and checking if it works now.

If it didn't, you now can:

• Try jumping to definition,
• See it fail with No linked CIDER sessions
• Then, use the new command M-x cider-debug-sesman-friendly-session-p
• Copy its output (as visible in the *messages* buffer) and paste it here.

Thanks much - V