10.1.0

Just your typical minor release. Plenty of fixes and enhancements, few new themes.

Some deprecations language maintainers might want to pay attention to:

• htmlbars grammar is now deprecated. Use handlebars instead. (#2344) [Nils Knappmeier][]
• when using highlightBlock result.re deprecated. Use result.relevance instead. (#2552) [Josh Goebel][]
• ditto for result.second_best.re => result.second_best.relevance (#2552)
• lexemes is now deprecated in favor of keywords.$pattern key (#2519) [Josh Goebel][]
• endSameAsBegin is now deprecated. (#2261) [Josh Goebel][]