Adding serde (de)serialization as optional feature

[mdsherry]

Plus a couple of lint fixes

[SebRut]

Anything preventing this to be merged?

[mdsherry]

@SebRut : If you need this, could you explain the use case to me? The code in the PR works, but I don't know that it's useful, and that it does what people would actually want it to do.

[SebRut]

I was thinking about using this to deserialize time intervals for schedules from config files with serde. I think right now the workaround would be to have fields like "intervalMinutes" and convert these manually later.

[imstevenxyz]

I have the same use case as @SebRut: intervals deserialized from a config file.