Custom content editing by admins

[roman-yagodin]

• Add edit link to every HTML tag marked by .skin-custom-content class and having data-resource-key attribute.
• Edit link should be visible in edit mode and for admins/superusers only.
• Clicking on edit link should open edit form for corresponding string in the SharedResources.Portal-X.YY-ZZ.resx file, there YY-ZZ is culture code.
• Changes should be saved to SharedResources.Portal-X.YY-ZZ.resx file.
• Edit form could be implemented as a part of R7.Epsilon.Helper module (replacement for LayoutManager) with DNN TextEditor ASP.NET control.
• Edit form could show the content of host-level and system-level resource files in tabs.
• Superusers could be allowed to edit also host-level resource files, but not system ones.

This will allow much simpler way to skin customization.

[roman-yagodin]

It's probably better to have separate resource file like CustomResources.resx for those strings (#216). And if the ControlLocalizer could be configured to get resource files from folders accessible by portal admins (like /Portals/X/Skins/R7.Epsilon/App_LocalResources) then it will leverage the need of implementing editing UI.

In this case, it would be sufficient to provide some kind of tip to superusers/admins in edit mode (#215) about the resource keys used for the string/content in place.