Refactor time series charts API

Remove stacked bar options from time series charts, add left bar offset,
and perform general refactoring.
Finish refactoring time series charts.

Finishes the work started by Chris on time series charts. Mostly just a
couple of bugfixes within that.

Author: Dylan Nugent
Implement a data centering option for time series bar charts

This adds an option to time series bar charts to set whether the value
being passed to the bar should be considered the middle, start, or end
of the bar. For instance, if passing values that are set to be end
values, the bar will be drawn so that the right side of the bar aligns
with the time point on the axis instead of the center.

Author: Dylan Nugent
Implement more useful value labeling.

Add independent value formatting for axis ticks and hover values on
charts that have axes displaying values. Ticks display unrounded but
SI-prefixed values, ensuring that two ticks showing the same value due
to rounding to a significant figure below the tick delta never happens.
Hover values show value to fixed precision of 2 numbers after decimal,
and formatting value for hover only can now be overridden with
"formatLabel" instead of "formatValue" variable to reflect that this no
longer updates the value formatting used on the axes.

Author: Dylan Nugent
Update example app and documentation with stacked bars removal.

Remove documentation and example options pointing to stacked bars as an
API option for time series charts, as they are removed by Chris's time
series refactoring project.

Author: Dylan Nugent
Fix some PR comments, to squash

Will be squashed into axes labelling commit before being merged.

Fix variable naming of formatLabel vs formatValue, move value axes
computations into axes helper, and fix value axes looking at largest
number instead of number of greatest magnitude and looking at pre-scaled
domain instead of axis domain.

Author: Dylan Nugent
Revert "Revert "Reverts change from templateName to layoutName""

This reverts commit 4d0d7105fd41f7f15e836627ba8fd761724cd205.
Temporary workaround for axes labelling

Center the axis label on time series if and only if there are bars to
show where they go. This is a temporary proof-of-concept and shouldn't
be merged.

Author: Dylan Nugent
Fix quarter labelling for proof-of-concept axis shift

I'll be making this a legitimate API extension instead of a demo
eventually, for the meantime just fix up labelling.

Author: Dylan Nugent
Fix rounding in horizontal bar chart