v0.4.0

AbstractDifferentiation v0.4.0

Diff since v0.3.0

Closed issues:

• value_gradient_and_hessian for ForwardDiff returns gradient of type Dual (#46)

Merged pull requests:

• Make tests more modular (#27) (@sethaxen)
• Implement backend for ReverseDiff (#29) (@sethaxen)
• Implement backend for FiniteDifferences (#37) (@sethaxen)
• Make ForwardDiffBackend an AbstractForwardMode (#38) (@sethaxen)
• Add citation (#42) (@ChrisRackauckas)
• Implement backend for Tracker (#44) (@sethaxen)
• Add some missing primal_value methods (#47) (@mohamed82008)