Implement hyphen ranges

[mbrubeck]

The version requirement 1.2.3 - 2.3.4 should be equivalent to >=1.2.3 <=2.3.4.

Spec: https://docs.npmjs.com/misc/semver#hyphen-ranges-x-y-z-a-b-c

[dtolnay]

Per https://github.com/dtolnay/semver/tree/1.0.0-rc.1#scope-of-this-crate, I am going to consider this out of scope for this crate until there is an accepted Cargo RFC. If the Cargo team wants hyphen ranges in Cargo then we can update the implementation here.