fixed a bug where clicking on/moving a textbox by its rubberband whith stylus tool on text caused a crash (more frequent after zoom out)

fixed a bug where thumbnail view was not centering on the active thumbnail view, when clicking on the Next Icon (main bar)

Revert "workaround to adress badly attached thumbnail views (no more time to investigate on it...) + prevent overwriting scenes"

This reverts commit 0fd15f62.

workaround to adress badly attached thumbnail views (no more time to investigate on it...) + prevent overwriting scenes

This reverts commit b6f41165.

This ensures distance from previous point is calculated correctly

Erasing part of (but not the entire) center cross of an arc drawn with
the compass caused a crash.

Removed 'Set as background' button for images, since that feature is now accessible from the image menu on the board

Web results still show the details which include some metadata about the
image retrieved, for example.

This is now a setting so it can easily be re-enabled if desired (which
could be useful especially if we decide to also display metadata of
local items)

-> also deleted obsolete UBInterpolator classes