Merge branch 'release-3.0.0'

Merge branch 'release-2.0.2'

Merge branch 'release-2.0.1'

Merge branch 'release-2.0.0'

Closes #3.

Merge branch 'release-1.3.0'

Merge branch 'release-1.2.0'

Fix parens spec parse pattern

README improvements

- clarify examples
- clarify rationale

Re-order README sections.