Tagging 2.8.5

Including docs and tests.

Closes #98.

Tagging 2.8.4

A leading zero is forbidden in the SemVer spec, but could be valid under
other schemes; when coercing, it can easily be removed.

Closes #89, thanks to Andrew Ni for the report.

resolves #87

Thanks to Nathan Walters for spotting this.

Npm ranges with a `<X.Y.Z-P` component were not properly expanded:
they were converted to:
    <X.Y.0 || (>=X.Y.0 && <X.Y.Z-P && no-prerelease)

The correct expansion is:
    <X.Y.0 || (>=X.Y.0-* && <X.Y.Z-P)

Closes #86.

This function allows developers to preview the structure of the
resulting clause parsed from a spec, usable with
`print(spec.clause.prettyprint())`.

Apply typical PEP8 indentation rules.

Tagging 2.8.2

This (deprecated) property failed when used on a `Spec` item based on a
single-term range (e.g. `==0.1.2` `<2.0.0`).

Closes #82.

Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>

This attribute wasn't meant to be removed.