VERSION 3.42: new preview and new cool Tentacle-effects

I have completely re-implemented the preview now, so that it is also using the compute-shader-pipeline and produces images which are more close to the final renders. And more important, it can also render very "heavy" scenes, which was the largest problem before. You will encounter increased initial shader-compile times, but the shader compile time between preview and final render will be reduced. So, it is not really slower, even if it might feel like that at the beginning.

Also there are two new Tentacle-releated features: a primitive and a Surface Effect. Thanks to Brad Stefanov for suggesting that feature!

Complete changelog:
VERSION 3.42.2694 (06.05.2026):
- mandelbro3d:
- added new "Tentacles"-surface-effect (but please beware: this one is really complex and needs a lot of time
to compile!) (SWAN-1518)
- created preview-images for the surface-effect-picker (SWAN-1521)
- improved stability/quality of the displacement of surface-effects (SWAN-1522)
- add Checkerboard3D procedural texture (SWAN-1519)
- fixed: the bricks-procedural-texture ignores the z-offset (SWAN-1520)
- fixed: when loading an animated scene with frame != 1, the preview shows the right frame, but
not the frame slider (SWAN-1512)
- procedural textures: add offset parameters for positioning the texture (SWAN-1502)
- improved stability/quality of the displacement of surface-effects (SWAN-1522)

VERSION 3.41.2686 (05.05.2026):
- mandelbro3d:
- new Tentacle Field primitive (SWAN-1510)
- when mapping a single fractal into a hybrid, the hybrid should inherit the material and colors from
the fractal (SWAN-1511)
- added "Wrap into Container"-button also for hybrids (SWAN-1517)
- fixed: when enabling a post (affine) transform at formula level in a fractal formula which is inside a hybrid,
the shaders got not recompiled and all changes to the transform-parameters had no effect (SWAN-1499)
- added support for the "Headlamp"-mode for the new preview as well (SWAN-1514)
- fixed: the light-settings for "Headlamp"-preview-mode where permanently hidden (SWAN-1505)
- fixed: after activating a previously paused preview the label "Computing shaders..." was not displayed (SWAN-1501)

VERSION 3.40.2679 (04.05.2026):
- mandelbro3d:
- re-implemented the preview based on compute shaders, by using the main rendering pipeline to
achieve more close results between preview and final render and support heavy scenes better (SWAN-1500)
- added add Folding Int Power formula (SWAN-1503)
- changed the default scene to use one direct light instead of multiple soft lights (SWAN-1507)
- fixed an iteration- and bounding-related bug in the Mandelbox-family of fractal formulas (SWAN-1508, SWAN-1506)
- fixed: enabling/disabling sphere inversion transform did not work in a relaible way (SWAN-1509)
- fixed: some of the new primitives could not be added by using the item-picker (SWAN-1498)
- the "Variation Floor"-primitive has now an option to control the repetition of the texture (SWAN-1246)
- fixed: the "Variation Floor"-primitive did not use the item-picker to select variations yet (SWAN-1513)
- also allow hybrids into the Scatter-container (SWAN-1516)