Moving config parsing to `serde`

[ChristopherJMiller]

I believe a lot of complexity could be removed by swapping config parsing from a manually process with yaml-rust to object deserialization with serde with it's derive feature and a supporting yaml deserializer.

The Intermediate types could be removed as the deserializer understands optional parameters. To handle defaults, the attributes on config can be made private and getters can be implemented that access self and unwrap to a default if they were not set. The mode "serial" or "parallel" can be mapped properly via the derive attribute macros on enums.

This could also ease the work involved with #265

Thoughts?

[artem-zinnatullin]

Sounds good, I'd like to get rid of intermediate_config stuff

mainframer/src/intermediate_config.rs

Line 16 in dc6e11d

pub struct IntermediateConfig {

Just make sure to keep config validation :)

[artem-zinnatullin]

Heads up: @ChristopherJMiller pls make sure you're on updated 3.x branch when you start working on this, I've merged quite a few infrastructure updates in last few days 😬

[ChristopherJMiller]

PR is up at #282 !