Add 'timeAxisMode' parameter

This fixes Issue #3 by adding a parameter that enables
compressing the time axis range to be from the start of the earliest
event to the end of the latest event in the search results.
Small cleanups
Merge branch 'ben-roling-timeAxisMode'
Make sure the category label is visible
Force a minimum height for rows (so empty categories in compacted mode don't look bad
Really force minimum height