Headless Context cannot be created without EventsLoop

[Osspial]

After the changes in #1029, headless Contexts cannot be created without creating an EventsLoop. This is a small step back from the previous API, which let you do so without a corresponding EventsLoop. How necessary is this change? If we can allow headless Context creation without EventsLoop creation, we should probably allow it.

cc @zegentzy

[goddessfreya]

Windows was previously making the EventsLoops silently: see here, now it's just your responsibility to make it.

IOS never did support headless stuff: see here, nor did emscripten, see here

MacOS does not currently use the passed EventsLoop, see here. Nor does android: see here.

Additionally, OsMesaContext doesn't need an EventsLoop either (see here), however, please note that when shareable_with_windowed_contexts is true, we instead use the hidden window method, which does need an EventsLoop.

I guess we could accept an Option<EventsLoop> instead of an EventsLoop for headless contexts, however, in most platforms 'None' will just lead to a panic. I won't be available till this weekend I think, but I imagine this change would be trivial.

[Osspial]

Thanks for the explanation! It doesn't look like there's a good reason to support this then, so I'll close this.

[unlimitedbacon]

Can this be reconsidered? I'd like to run my program using an OSMesa context in an environement where neither X11 nor Wayland are available. As far as I can tell this is not possible right now since an EventsLoop is required.

[goddessfreya]

@unlimitedbacon That was an oversight... sorry. Fixed at #1058

[unlimitedbacon]

Thank you