v0.4.0 (2019-07-16)

Diff since v0.3.1

Closed issues:

• Improve mul_rev (#28)

Merged pull requests:

• Project.toml (#37) (dpsanders)
• removed duplicate definition (#36) (kaarthiksundar)
• Fix failing atan_rev test (#30) (dpsanders)
• Improve mul_rev (#29) (dpsanders)