Agda standard library version 1.6

Tidy up CHANGELOG for release candidate 1

Agda standard library version 1.5

Cleaned up CHANGELOG for v1.5 release candidate

Agda standard library version 1.4

Agda standard library version 1.4 - Release candidate 1

Agda standard library version 1.3

Agda standard library version 1.2

Agda standard library version 1.1

Agda standard library version 1.0.1