v0.18.0

What's new

Tons of new features, all from @tstack:

• [lib] if _timeslice is used in an aggregate, include it in the sort keys by @tstack in #149
• [funcs] add some more functions by @tstack in #150
• [lang] first-class support for durations in expressions by @tstack in #151
• [lang] add the "if" operator by @tstack in #152
• [lang] add support for logical and/or expressions by @tstack in #153
• [lang] support regex option for parse operator by @tstack in #154
• [lang] raise an error if percentile is out-of-range and fix default name by @tstack in #156
• [tidy] fix clippy issues by @tstack in #160

Full Changelog: v0.17.0...v0.18.0