Build 2.0 target 2.0
First prototype of libprefs refactor

Cherry-picked 'Fix alternate title injection to behave exactly as the earlier non-libprefs preferenceloader did'
Stash the source bundle in the PSSpecifier so that it may be reused
Fix navigationTitle causing a crash (fix titles in general)
Fix crash bugs related to (and display error pages regarding) foregrounding state restoration
Support loading specifiers from the 'items' property of a PSListController's specifier
Use the internal generator for libprefs.