Fix y-axis graph padding

[jaredscheib]

• CHANGELOG.md updated
• Rebased/mergable
• Tests pass
• Sign CLA (if not already signed)

Connect #881

The problem

Graph did not properly display highlighted range when value for "greater than" rule exceeded local data peak value. This bug also showed up in "inside range" and "outside range".

The Solution

• Fixed the math for adding and subtracting padding.
• Removed incorrect and arbitrary "top" argument to allow "range" rules to display correct highlighting regardless of which value was greater.

Fixed display for "greater than":

[121watts]

This look good to me. Also checked out the branch and everything seems to be in order. Only thing missing is some tests. Specifically for the bug that's being fixed.

[jaredscheib]

Cool, thanks! Getting to tests now and will come back with something.

[jaredscheib]

@121watts I added a couple of preliminary tests for your perusal.

Questions:
Maybe I should be generating random values?
Maybe multiple assertions should be in multiple tests?
Maybe the description is unclear?
Maybe the variable names aren't great?

[121watts]

@jaredscheib Once you update the CHANGELOG this is good to merge!

[jaredscheib]

Cool, done!