added display() and color() getter/setters to Axis to allow easier control over appearance of an Axis
Merge pull request #68 from Stavrakakis/master

bugfixes, typos and new Axis display functionality
tidied up how stacked/grouped series refer to the current series being drawn in the group (series.currentSeries)

fixed reference to self instead of this that didn't work
renamed loop variable to make it clear it's an index
Merge pull request #69 from Stavrakakis/master

tidied up how stacked/grouped series refer to the current series being d...
Fix gridlines for charts

Adds the gridlines back in, horizontally and vertically. Gridlines are
now clipped to be within the plot area of the chart, and line up with
the tick marks.

Also modified the gridlines() setter function to update whether or not
gridlines are visible for the chart.
Method renaming

Renames this.gridlines => this.showGridlines
Adds this.gridlines (again), returning a readonly array of all current
gridlines on the axis.
Adds tests for gridlines

Adds some new unit tests for gridlines.
Also defaults the gridline colour to the colour of the axis.
Remove redundant comment

We no longer comment out this.drawGridLines, so don't need the comment
explaining as such.
Merge pull request #70 from tpkelly/master

Fix gridlines for charts
Autosize margins

Makes the chart resize whichever margin it uses for its x and y axis.
Makes the series provide sizings of all labels on x and y.
Adds tests that the correct margins are set.
Properly key data for longest label

Uses this.dataset() instead of this.data() to extract the values.
Pull out gridlines to new class

Pulls out the drawing code for gridlines into its own class, ready to
add some styling methods to it.

Also updated the test to remove the chart before doing the expect() call
to make sure it gets removed properly.
Allow custom line width and colour

Adds the lineWidth/lineColor getter/setters, and hooks them in to the
gridline drawing.
Merge pull request #71 from tpkelly/master

Autosize margins
Merge pull request #73 from tpkelly/master

Refactor gridlines
Updates to sorting and mean calculations as part of the chart requirements
on the front page of the gh site
Uncouple series and chart

Pulls out the chart argument from a series constructor, and makes sure
the series has no back-references to its parent chart.
Renames chart.chart => chart.plotArea

This had been confusing me a lot, as I thought chart.chart was the same
as chart. Turns out its the HTML node for the corresponding chart, where
we add all our lines, points, etc. It makes more sense to differentiate
it by calling it a plot area.
tidied up some comments and removed computeFunction() until custom post aggregation can be rethought