Changing the style
Although things like thickness can be modified by adjusting the brush, rendering things
like dashed-lines require changing the style of the brush.
Styles are defined by an array of allocated colors which represent the desired style which
is then registered using the imagesetstyle() function.
<?php
$dashed = array($black, $black, $black, $white, $white, $white);
?>
Once a style has been defined, it can be used with any GD drawing function by setting the
color to IMG_COLOR_STYLED
