Fix vertically overlapping value and row labels

[leeper]

The current binning algorithm simply puts labels on new lines when they're too close. A better version would evenly space the numbers within the range of overlap. It will have the same even appearance, but probably line up better with slope lines.

[leeper]

The new draw approach used as of 69f6143 eliminated binning altogether. Will need to think of a new way to do this by, possibly, modifying y-values that are near to one another in the segmentize()'d matrix.