- `hashmap_insert()` no longer takes key as argument, and
takes the pointer to be associated with the entry as argument.
- Rename `hashmap_entry_delete` -> `hashmap_delete`.
- Make `user_data` the first argument for `hashmap_walk_func`.
- Other misc renames.
- Use negated errno as return value.
- Do not consider deletion of the watched file as a fatal error,
and use a separate error code to distinguish between them.
- Lazy-init worker: Starts watching upon the first call to
watcher_poll().
- Always lazy-init watcher when possible.
- Add a check in `backend_create()` that fails when the bookmark
storage does not exist, so that function behavior is more
consistent on different platforms with and without sandboxing.
- Only check Landlock flags on Linux.
Fix a regression in commit d1dac54b72 where sys/stat.h is no longer
included in backend_firefox.c and backend_chromium.c.
It has to be explicitly included for the UTIME_xxx macros.
There were bad code changes that cause the compiler to complain or
panic, but went unnoticed since they are only built if toggled with
`--enable-xxx` or `--disable-xxx` during build configuration.
Fix them altogether.
Do not check if the bookmark title is a valid filename,
as we said in the user manual.
However, we should ensure that the string does not contain
NUL characters, since we assume that a valid bookmark storage
should not contain bookmarks with such names.
