New features (multi colour bar graph + text wrap)

Added new function 'setBarColors' which takes an array of names and colours e.g. array("really long title"=>array("blue","red","green"), "Mary"=>array("yellow"), "Joan"=>array("red")). This allows the user to define different colours for each bar (either one or multiple).

Added text wrap, if setXValuesHorizontal(true), the text will be wrapped to show one word per line.

I have attached an example image (test1.png, test.php) in the examples directory.