Add params 'highlightLines', 'arrowLines'

Add 'highlightLines', 'arrowLines' to ExecutionVisualizer params, to allow client to determine how highlighting is done by visualizer. Also, add a no-arg URL param 'highlightLines' for iframe js that will turn on highlightLines and turn off arrowLines in the embedded instance. 

Demo:
http://cscircles.cemc.uwaterloo.ca/vis-demo/
http://cscircles.cemc.uwaterloo.ca/java_visualize/