Merge pull request quantumlib#182 from MichaelBroughton/const

Added const to AddState functions.

Merge pull request quantumlib#177 from quantumlib/release-0_3

Release version 0.3.0

Merge pull request quantumlib#146 from quantumlib/dot-two

Update to v0.2.0

Merge pull request quantumlib#143 from quantumlib/stateful-for

Convert to stateful for.

Merge pull request quantumlib#126 from quantumlib/qsimcirq-release

Upgrade to v0.1.0 and document release.