Comment 12 for bug 793420

Layer visibility fixed in:

 https://github.com/KiCad/kicad-source-mirror/commit/8722fd9c6c327407d7fe285e944830b1a9a9c57b

I considered Wayne's recommendation of doing the Design Settings at the SCH_BASE_FRAME level, but we'd need to write a whole boatload of operator== routines to make that work, and it would be inconsistent with most of the rest of the app which sets modified at the UI level.

The patch therefore fixes all callers of SetDesignSettings (both PCB_BASE_FRAME and SCH_BASE_FRAME), as well as callers of SetZoneSettings.