Fix finding min/max in data for bins in histogram

Using .sort() and then getting the first and last elements gave very
weird results.
Namely the max was always near a power of 10 (100, 1000, etc..)
Just going through all elements fixed this
Add docstrings for show_id and element_in_viewport
Trust flot to make sensible ticks

Without decimals it’s hard to make ticks for event rate
Filter -999 data points

Ignore -999 values when trying to find minimum bin for histograms