DART 6.8.4

Changes

• GUI

  • Fixed crashing on exiting OSG + ImGui applications: #1303

Compilers Tested

• Linux

  • GCC 64-bit: 5.4.0, 7.3.0, 8.2.0
  • GCC 32-bit: 5.4.0

• macOS

  • AppleClang: 9.1.0, 10.0.0