Compared to Corrade, the improvement in compile time is about a minute
cumulative across all cores, or about 8 seconds on an 8-core system (~2
minutes before, ~1:52 after). Not bad at all. And this is with a
deprecated build, the non-deprecated build is 1:48 -> 1:41.
This was an annoyance with GltfImporter's customSceneFieldTypes, where
it just wasn't possible to set the options through AnySceneImporter or
magnum-sceneconverter -i argument without causing a warning to be
printed.
The behavior is now that if a plugin configuration subgroup (but not the
root group) is empty, it's assumed that new values are meant to be added
to it, and thus it doesn't warn on them.
Initially, if possible, by extracting the code into separate files and
testing those, instead of having to execute a binary and deal with
output redirection and other crazy things. The option propagation is
already extracted, so do that first.