Improve colours used for bar chart series and pie chart data points

[David Platten]

The colours for bar chart series are not very appealing when more than two series are being plotted. The colours used for pie chart data points are generated using a routine that I have written, but it is not very elegant.

I would like to make use of a pre-written library, and think that chroma.js (http://github.com/gka/chroma.js) will work well. It will enable the use of colour scales similar to those on the ColorBrewer site (http://colorbrewer2.org/): http://github.com/gka/chroma.js/wiki/Predefined-Colors.

I have already implemented this library when working on issue #332, but thought that it was worth having it as a separate issue.

[David Platten]

See commits 1c3bf6c and 35e6bfd

[David Platten]

Added user option to plot a series per system, or to group all systems into one series. Also fixed an error in the colour calculations that was causing a divide by zero when there was only one series. References issue #332 and issue #342.

→ <<cset ec745250d1f6>>

[David Platten]

Added border around each datapoint. Helps to see series that are plotted with a light colour. References issue #342

→ <<cset 9582a060f19e>>

[David Platten]

Updated radiographic charts to use new colour scheme. Also fixed a couple of errors: put back in some code that should not have been removed. References issue #332 and issue #342

→ <<cset 04b29547f7dc>>

[David Platten]

Simplified call to radiographic data calculation. Fixed problem with over-time colours. References issue #332 and issue #342

→ <<cset 91d34c39b579>>

[David Platten]

Fixed another problem with over-time colours. References issue #342

→ <<cset b65671eed21e>>

[David Platten]

This is now working as I would like.

[David Platten]

Added user option to plot a series per system, or to group all systems into one series. Also fixed an error in the colour calculations that was causing a divide by zero when there was only one series. References issue #332 and issue #342.

→ <<cset ec745250d1f6>>

[David Platten]

Added border around each datapoint. Helps to see series that are plotted with a light colour. References issue #342

→ <<cset 9582a060f19e>>

[David Platten]

Updated radiographic charts to use new colour scheme. Also fixed a couple of errors: put back in some code that should not have been removed. References issue #332 and issue #342

→ <<cset 04b29547f7dc>>

[David Platten]

Simplified call to radiographic data calculation. Fixed problem with over-time colours. References issue #332 and issue #342

→ <<cset 91d34c39b579>>

[David Platten]

Fixed another problem with over-time colours. References issue #342

→ <<cset b65671eed21e>>