add example: stream video capture over http

[tidely]

No description provided.

[tidely]

Some checks seem to be failing. Older versions of opencv (3.x) appear to have VideoCapture::new_default instead of VideoCapture::new_def as in 4.x. Additionally VideoCaptureTrait doesn't appear to be used.

I'll switch to VideoCapture::new since it's consistent across all versions. A workaround for the VideoCaptureTrait would be to import the prelude, but I'd prefer putting a #[allow(unused_code)] and leave a comment explaining why. @twistedfall which way would you prefer it

[twistedfall]

I’d say don’t bother to support v3.4 too much. Do it only if it’s easy. This branch doesn’t seem to be supported upstream anymore so I expect to deprecate it too in the not so distant future.

[twistedfall]

Thank you!