Merge pull request sonic-pi-net#3133 from lilyinstarlight/fix/qt-5-12…

…-qrecursivemutex

GUI - fix Qt 5.12 recursive QMutex usage

Merge pull request sonic-pi-net#3118 from sonic-pi-net/dev

v4 Release

Merge pull request sonic-pi-net#2684 from sonic-pi-net/v3.3.1-dev

V3.3.1 dev