SO's auto rotation has its own rotation logic that ends at fixed positions. This collides with the "to nearest" option whose aim is to rotate to the next sensible state taking into account from what position the rotation was started.
Thus the solution is to disable SO's auto rotation while the cube is rotated.
fixes bug 4495
- add missing edge faces
- implement a proper rotation recipe -> rotate towards the nearest possible state
- add preferences settings to turn off this new rotation behavior
- get rid of transparent cube faces to avoid wrong clicks, this way also remove the backfaces
- to make the edge faces fit, use triangles for the corners
- expose cube size setting to preferences dialog
- add new button to view backside
- get rid of bitmaps because as reported in https://forum.freecadweb.org/viewtopic.php?f=3&t=52118&start=20#p481781
the x y z labels are not scaled on HiDPI screens
moreover they are often "in they way" when you want to click on a corner and in principle they don't provide more info since we already have the CS with the axis labels
- also fix an arithmetic overflow compiler warning
- also rename 2 variables
By default navigation cube text now has more weight and CS axes are slightly shifted. A few additional parameters have been added, for being able to customize navigation cube offset, colors, font and visibility of CS. Parameters are consolidated under NaviCube group. Customization front-end, making use of this new parameters, will be added to CubeMenu module in the following days:
https://forum.freecadweb.org/viewtopic.php?f=34&t=43338
+ handle destruction of GL context in 3d viewer class
+ fix for OpenGL error message: 'Texture is not valid in the current context. Texture has not been destroyed'
