dynamic module list

[sthibaul]

Is your feature request related to a problem? Please describe.
After installing a speech dispatcher module, one has to reload spd (and possibly screen readers ; orca doesn't need it) to get the module available

Describe the solution you'd like
speech dispatcher should notice modules dynamically and make them available

Describe alternatives you've considered
The user can reload spd, with SIGHUP it's then to the screen reader to get the list of modules again (orca does). It'd probably still be useful to make sure that that works in case spd crashes, but better not have to restart spd.

Additional context
The first thing needed for that would be to make the module list dynamic in the ssip protocol itself. And then spd could use e.g. inotify to watch the module configuration directories (or if not available, just probe from times to times), and load modules on the fly.

[sthibaul]

To be noted: one doesn't have to restart spd completely, sending it SIGHUP (e.g. through systemctl reload) should be enough for it to reload configuration and re-check module list.

[sthibaul]

(SIGHUP actually already works with orca: it seems orca requests the list of modules when opening the preference menu, and doesn't keep a cache of it). So probably we can just implement inotify/probe support and already get nice module auto-load support.