Deprecate triggers and replace them with hooks. Now that aerc supports
running arbitrary ex commands over IPC, it is possible to run internal
aerc commands *and* shell commands via external shell scripts. Hooks
only allow running shell commands. Hooks info is passed via environment
variables.
Implements: https://todo.sr.ht/~rjarry/aerc/136
Signed-off-by: Moritz Poldrack <git@moritz.sh>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>
