Make editing of spinboxes more sensible

[kallaballa]

Doing a single edit (one key stroke) in a qspinbox will emit valueChange and the component loses the focus.
Instead it should wait for either the return key being hit or for lost focus before commiting the change.

[kintel]

This bug is caused by temporarily disabling GUI elements in ObjectPropertyWidget::disable():
https://github.com/Metalab/ctrl-cut/blob/master/src/gui/ObjectPropertyWidget.cpp#L235

disabling the elements causes them to lose focus.

[kallaballa]

but disable is not called in the pertaining slots. e.g. https://github.com/Metalab/ctrl-cut/blob/master/src/gui/ObjectPropertyWidget.cpp#L256

[kintel]

It is. Follow the trail starting at https://github.com/Metalab/ctrl-cut/blob/master/src/gui/ObjectPropertyWidget.cpp#L58

[kallaballa]

you were right. fixed