v0.2.8

TimeSpans v0.2.8

This version is branched off of v0.2.6 to provide features included in later versions to users who can't yet upgrade to v0.3.

Diff since v0.2.6

Merged pull requests:

• add Statistics.middle (#25) (@palday)
• Add invert_spans (#36) (@mich11)
• Backport features introduced in 0.3.x to 0.2.x (#38) (@ararslan)