Fixed incorrect API documentation.

Reordered some statements for clarity.
Documented rare bug with TODO.
Extended API documentation.

Refactored animation code to hide 'private' function 'animate'.
Allow 'render' to be called with no arguments.
Clearer definition of default options.
Config option to control max/min label precision.
Added 'borderVisible' chart option.
Consistent handling of default series presentation options.
Added 'linear' as a synonymous alternative to 'line' interpolation mode.
Set series strokeStyle to 'none' to disable drawing of series line, allowing a filled series with no line.
Created 'builder' page, allowing new users to experiment with chart options and generate the corresponding code immediately.

Converted 'customisation.html' into 'builder/index.html'.
Update to version 1.18.
Added HTML5 doctype to all pages.