hgview #109851 Have a persistent layout for toolbar [validation pending]

What has been hidden, etc. should be remembered across loads.

(beware to not do that for the full hidding of the toolbar until we have a way to display it again.

priorityimportant
typeenhancement
done in1.8.0
load0.500
load left0.000
closed by#7cee5f88daec [qt] remove toolbar visibility config entries (closes #109851), #519b4a226b8c [qt4] persistent toolbar visibility (closes #109851)
patch[qt] remove toolbar visibility config entries (closes #109851) [applied][qt4] persistent toolbar visibility - remove configs (closes #109851) [applied]