This adds a fallback that kicks in if the permissions are missing to
access "happy.yml", by using the current date to infer the expected
semester name.

If this is not done, etags fails when invoked later on as the file is
read only (r--) and cannot be written (rw-).

We use 'spt--remote-cip-desc' in 'spt--eval-in-cip', as this contains
the proper repository configuration for the CIP.

Useful to check the CI status.

This is mainly to avoid accidentally corrupting their contents and
having to fix these again.

Keeping in mind that 'process-file' works on remote systems.  While I
don't actually use this, it would help in avoiding some peculiar edge
cases.

As it turns out that the main use of 'spt-participation' was to select
a submission manually right afterwards, it seems adequate to merge
these two operations into one, seeing as there is no real use to just
having a purely informative 'spt-participation' command.

While it is slower, the diffs are ultimately easier to read in case of
a conflict and we avoid all elision, that might render the state file
partial and inconsistent.

This is a simple hack to prevent overwriting other comments, that
could arise when switching between files.

The most important change here is that the code will now ensure the
right Email address is used to send the messages.

Previously an accidental M-n or M-p could skip to the next comment and
thereby discard incomplete data.  By using the buffer modification
status, this issue should be avoidable by relying on naive
functionality.

I have managed to confuse myself with this variable name, so it
doesn't hurt to have a more explicit name.