Initial draft of new title view on Months screen.

Uses NavigationTitleScrollView and manually
translates the latter's content offset based on
the collection view's, for the illusion of section
headers becoming navigation titles. Heavily
refactor the old procedure for compactness and
clarity. Extend it with an intermediary
offset-updating stage, during which index changes
are not committed.

Also fix a NavigationTitleScrollView layout bug
for non-paging variants (nothing visible). Add
missing textColor syncing with subviews. And add
missing explicit protocol conformance.
Re-implement default title setting on Months screen.

Includes refactoring text formatting.
Minor custom title view nib height tweaks.

The Event screen title can fill a portrait nav-bar
because there is no landscape support. Note the
custom title views do not auto-resize.
Refine Swift usage, minor coding style tweak.