[kernel.graphicsGL] Simplify the billboard computation
org.fortiss.tooling.graphicsGL.ui.util.GLPrimitives.createBillboardMatrix(float[],
Vector3f, Vector3f, Vector3f, Vector3f)
can be simplified:
- right vector is cross product of look and up
- look vector is vector from camera to pos
new method interface:
createBillboardMatrix(float[] bbmat, Vector3f camera, Vector3f pos,
Vector3f up)
(from redmine: issue id 3372, created on 2018-04-09, closed on 2019-05-29)