Changes

Cache now also updates on create, rename, delete

The cache wasn't update when a file was created, renamed, or deleted.
Tasks would then list double (as the original and the one from the
renamed file, for example).

The cache now subscribes to further vault events in order to stay in
sync with the vault.

Task blocks now list all tasks by default

When including tasks via a ```tasks block, the results now shall all
tasks by default, regardless of their indentation.

There is now a new query option exclude sub-items to re-enable the
original behavior.

Before, the result list would only show top-level tasks, which was
confusing.