add support for toml 1.0

[ordian]

• toml_edit doesn't properly handle quotes in strings #128
• Dotted keys are not supported #91
• Verify encoding is compliant

[joseluis]

Toml 1.0 has finally been released, and here is the updated spec (link in OP is dead):

https://github.com/toml-lang/toml/blob/master/toml.md

[ordian]

The spec is available here: https://toml.io/en/v1.0.0

One of the major changes is adding support for dotted keys. There is a WIP PR for that #73, but it hasn't been moving forward recently.

[epage]

Splitting out of rust-lang/cargo#5586.

Just wanted to double check before you leave that you are good with continuing forward with updating the parser as-is or if the lexer re-work needs to be done and done first. If so, I'll take up #73 and other conformance work for 1.0.

[ordian]

I think reworking the lexer #57 (if there is a consensus it needs to be done) and comformance to 1.0 are two independent tasks.

[epage]

I'm going to declare us implementing 1.0 but with an open bug (#128)