v0.5.9

Zygote v0.5.9

Diff since v0.5.8

Closed issues:

• Error with broadcasting == (#724)
• Nan gradient for elu and selu. (#758)

Merged pull requests:

• Changes needed for Julia 1.5 (#772) (@DhairyaLGandhi)
• support ChainRules AbstractZero types (#786) (@mzgubic)
• Use === when testing equality with nothing (#790) (@samuela)
• fix error while broadcasting (#793) (@gxyd)
• Correct primal of Matrix from UniformScaling & handle sum of boolean arrays (#794) (@oxinabox)
• remove submodule (#805) (@CarloLucibello)