jMonkeyEngine: jMonkeyEngine 3.9.0-alpha4

From jMonkeyEngine: link to the original post

What's Changed

• VarType: javadoc by @capdevon in #2519
• Refactor: AbstractShadowFilter reduce object allocations by @capdevon in #2516
• Feat: EmitterMeshFaceShape - enhance particle emission uniformity by @capdevon in #2503
• Support for switching platforms (from Wayland EGL to X11 GLX) by @JNightRider in #2500
• AWTSettingsDialog: javadoc + add AppSettings Preference logging by @capdevon in #2478
• #2541 move screenshots to docker by @richardTingle in #2542
• Changes pipeline lists to from LinkedList to ArrayList by @codex128 in #2543
• Fixed stencil reference handling in RenderState #2538 by @theMinka in #2539
• Fix inverted axis in gltf loader by @riccardobl in #2546
• Enhance BitmapFont and BitmapText Javadoc by @capdevon in #2534
• ArmatureDebugAppState: minor fix and improvements by @capdevon in #2531

Full Changelog: v3.9.0-alpha3...v3.9.0-alpha4