Realign marker text if cut by fixed edge

[edew]

Is your feature request related to a problem? Please describe.

As asked in #1577 there is no way to currently align labels so that they are not cut when near a fixed edge.

In the case that the edges are not fixed this is OK since the chart can be scrolled to view the full text. With fixed edges this is not possible.

See the images below for examples:

Describe the solution you'd like

When rendering marker text, if the "half-width" of the text is greater than the number of pixels between the marker's data point and the edge of the chart then the marker should be shifted to the left/right so that all the text is visble.