Enums and bitmasks

[PMeira]

A few enumerations are used in bitmasks or mixed enum+mask. Currently, CEnum doesn't allow this.

An interim fix was added for Monitors.Mode in #75 (just allow integers without restricting to the enum values), but a more elegant solution would be better. I also noticed a few projects vendor CEnum and modify it, for example https://github.com/JuliaGPU/VulkanCore.jl/pull/17/files

Looking for alternative packages, so far I found https://github.com/jmert/BitFlags.jl
Should we adopt it here?

[kdheepak]

Yeah, I think generally we can do a lot to make a more Julian interface here.

[kdheepak]

I will look into those packages. I seem to remember solving this for work differently. When I’m back at my work computer I’ll try to find that solution and paste it here.

[PMeira]

I'm adding BitFlags.jl as a dep for #82. We can update the enum usage for the other modules later if it's seen as a better experience.