0.8 RC

The release candidate for 0.8 is a relatively incremental change, as beta seemed to be doing generally fine, with only minor (and not even that necessary) tweaks here and there and the documentation update.

What's changed in code

• asKeyValueRange: support accepting rvalues (by @KitsuneRal in #671)
• Tighten up logging categories stuff (by @KitsuneRal in #672)

Full Changelog: 0.8-beta1...0.8-rc1