J. Ryan Stinnett 11e274b477 Add spans feature to control proc-macro2
Using `proc-macro2`'s `nightly` feature is a good default for most use cases.
However, it causes a build error if used together with crates such as
`cssparser` that also use `proc-macro2` from a build script.

This change adds a default enabled feature `spans` that users can disable if
they need to work around this conflict.

Fixes #160.
2018-04-25 14:42:21 -05:00
..
2018-03-29 14:50:40 -07:00