Adding time32 vars and a frame index.
This adds a FrameIndex that tracks frames better. This removes the nasty
copy/paste logic for duration calculation everywhere that was causing
precision issues.
'time32' var type added, though unused in the new world, for writing
times in a consistent way. Useful for future events (network/etc).
Redoing the framebar.
Moving the command/keyboard logic to the document view where it belongs.
Framebar is now shown above the zone that contains it, instead of globally.
The nav bar could have a framebar in it if we want, but otherwise will
be heatmaps/selection state/etc. Future commits will rebuild that piece.
Reworking the nav bar, part 1.
This merges a lot of functionality into the navbar, shares painters, and
generally makes things more useful. It also changes the app to only have
one active zooming viewport at a time, which paves the way for simplifying
viewport logic all over.
Cleaning up viewport logic and adding frame navigation.
Adding back view visible range display on the nav bar.
Fixing time range drawing.
Fixing click-to-clear-filter.
Exporting begin/endTimeRange.
Fixing multi-tiered time range rendering.
Merge pull request #199 from google/navbar

Navbar rewrite.
Merge pull request #198 from google/frames

New frame bar.