Fix ctkDoubleSpinBox::DecimalsByValue signals

Extra signals where fired by setValueAlways->setValue->setDecimals.
This is an issue when the intermediate signals are generating errors
(e.g. 0.1 -> 1.0 was generatign a valueChanged(0.) signal).
Merge branch 'fix-ctkdoublespinbox-decimalsbyvalue-signals'

* fix-ctkdoublespinbox-decimalsbyvalue-signals:
  Fix ctkDoubleSpinBox::DecimalsByValue signals