use auto-formatting

[danieleades]

the benefits of auto-formatting are many and varied, and are well-documented

summarily,

• it creates a consistent visual style across the ecosystem (rustfmt is almost universally adopted)
• reduces diff noise (primarily by allowing a contributor to autoformat their changes without affecting other code)
• obviates the need to ever discuss formatting in a PR again

I would personally strongly advocate for using the default config, but if there are any consistent differences in style from the default then these can be configured.

[dwrensha]

Is there a way to exclude the generate files capnpc/src/schema_capnp.rs, capnp-rpc/src/rpc_capnp.rs and capnp-rpc/src/rpc_twoparty_capnp.rs from this formatting?

[danieleades]

Is there a way to exclude the generate files capnpc/src/schema_capnp.rs, capnp-rpc/src/rpc_capnp.rs and capnp-rpc/src/rpc_twoparty_capnp.rs from this formatting?

i'll look into it. Why these files specifically?

anything with @generated should be skipped by default, i think

EDIT: not 100% sure what's happening here. according to this PR, @generated files should be excluded - rust-lang/rustfmt#4877

EDIT: got it. despite what the PR said, the config option was disabled by default. have added a rustfmt config file

[dwrensha]

Nice, and thanks @Timmmm for adding @generated in #153!