examples: add an example for estimating the pi

Merge branch 'develop'

Merge branch 'develop'

Bumping version to 0.5.1

Version 0.5 Stable

Tag 0.4.5

Tag 0.4.4

Tag 0.4.3.

Tag release 0.4.2

Bump version to 0.4.1

Merge branch 'jflatow-public'