Change remaining users of manifest flags

Switch to simpler manifestdict

Merge: use single objects for tracking manifests

Merge: save away mode bit so that we don't need manifest later

Merge manifest refactor work

Combine manifest dict and flags dict into a single object This gets rid of the need to track two objects and might save memory. This might be faster implemented as a subclassed dict with auxiliary functions to access a sparse flags dict.

manifestflags: eliminate remaining users of direct dict access

Use strings for manifestflags to allow storing multiple flags

Start using manifestflags methods

Add manifestflags class