Real time y axis does ticks by day and hour

These ticks are on six-hour intervals.
Small modifications to real time help text
Customize axis interval for different time domains

As the time domain expands, we now hide tick marks.
Hide overlapping thumbnails

They still can be selected with the arrow keys, but can't be clicked
upon.
Allow the user to load more realtime images
Add day/night color gradient for realtime images
Refactor daynight colors, tweak blue