Rethink @requires dependencies #476
Description
The startup time for Blink.jl almost entirely consists of the requires blocks here.
The WebSockets block is unnecessary because its a dependency anyway. Mux.jl is a small package that shares many dependencies. It's much faster to depend on it here than to include it in requires.
Blink.jl already depends on WebIO.jl - the code should just live in Blink.jl where it can be precompiled.
All up this reduces the package load time of Blink.jl (on my laptop) from 5 seconds to 1 second.
If people agree I can PR Blink and WebIO with the changes.