Replace the background_worker by an executor.

Introduce a new API to execute "runnables". The execution can be
automatically interrupted on timeout or via an explicit cancelation
request.

Size if never valid without target region (16x16), so
that face is unusable.

No need to pass the whole display config.

Only called on open and when it changes.

Don't write vd->fmt directly.

Unused since ad3c0ba1.

It's already done in the core.

We overwrite all the fields of sys->place further in Place().

We already have the "if" so make use of it.

We pass the new state and we received the modified value in the same variable.

Avoid some boiler plate copy for filters not modifying the output.

Hugo Beauzée-Luyssen authored Apr 21, 2020 and Pierre Ynard committed Aug 24, 2020

This reverts commit 64b59282.
This was working by accident, the language was interpreted as
user-agent and was accepted, only when english was used.

(cherry picked from commit 779b95f6)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

Better performance listing fonts with the previouly
matched family instead of criterion match

Makes use of explicit fallback to make a single
call to fontconfig.

Callbacks now returns error code
as we should be able to cache misses

It was lacking the same terminal '/' appending we do when a device gets
added, causing a mismatch depending on the SD module triggering the
removal

This allows the UI not to ask for a thumbnail generation if the previous
one lead to a crash, or if it's been failing multiple times before.