GAP.jl 0.9.0 released

Today GAP.jl 0.9.0 has been released.

Diff since v0.8.5

Closed issues:

• JuliaInterface manual: reference to \[\] and \(\) glitching due to MathJax (#786)
• Update to a newer package snapshot (#812)
• Upgrade to GAP 4.12.1 (#821)
• Failures with Julia nightly (#836)

Merged pull requests:

• Update to GAP 4.12.1 (#835) (@fingolfin)