Handle sync errors (set exit code accordingly)

Fix .conf to .yaml in goimapnotify config file

Rename muttrc variable

fix: `head` incompatibility between GNU and macOS

Replace head -n-1 with POSIX-compatible sed '$d'

chore: fix typo in README.md

The GNU-specific head -n-1 syntax causes errors on macOS/BSD systems.
Replaced with sed '$d' which is POSIX-compatible and achieves the same
result of removing the last line.

- syncandnotify() aborts early if mbsync or mpop fails
- mailsync aborts early (exit code 1, before notmuch) if all syncs fail

Added Bauhaus university weimar

$message_cachedir has been renamed to $message_cache_dir:
https://neomutt.org/guide/reference.html#3-244-%C2%A0message_cache_dir

This allows for the following command to work:

```
PREFIX=~/.local make install
```

The makefile already handles the `PREFIX` not being at `/usr/local`

Fix unary operator expected error

On my system running any `mw` command after a fresh install from the AUR, I get:

```
/usr/bin/mw: line 37: [: 1.5: unary operator expected
```

Now the script doesn't error per-se but it does set the `master` and `slave`
variables to wrong values. I'm also not sure how this wasn't raised before;
maybe that's a new bash version thing? I'm on 5.2.37.

Anyway I faffed around trying to fix this, in particular with the `-gt` operator
but it turned out that properly comparing float numbers is a pain in the butt in
bash. I found solutions using `bc` which I thought were weird.

To keep things simple I ended up doing a little substitution on the dot `.`
character and turned these nasty floats into integers, along with using the
`-gt` operator which did the trick on my system. May be unorthodox so feedback
is more than welcome.

Thank you for the great software by the way, lots of gratitude for your work.

This reverts commit 883e570d6d.

No mailsync with locked GPG key in non-interactive shells

Add goimapnotify for push notifications

fix(mailsync): delimit notification text from flags

Fix notify-send not coming through with goimapnotify

fix -P option description formatting in mw.1

Fix notifications for mails with multiline subject

Fix usages of mail/mails

Fixes text being interpreted as flags when it starts with a dash.
Try sending yourself a letter with subject starting with '-'.
E.g. if subject is '-10%' fixes error:
> Unknown option -10%

Signed-off-by: Jonas Dujava <jonas.dujava@gmail.com>

Signed-off-by: Jonas Dujava <jonas.dujava@gmail.com>

muttrc: use XDG_CACHE_HOME in notmuch integration

Fixes `sh: 1: cannot create /home/<username>/.cache/mutt_terms:
Directory nonexistent`.

cleanup Makefile

fix: rename variables

Added `fz-juelich.de` domain