Updated comment that gave incorrect information

Changed comment on line 56: "// Call vector heading function to get direction (note that pointing up is a heading of 0) and rotate"
To: "// Call vector heading function to get direction (note that pointing to the right is a heading of 0) and rotate".

This confused me greatly until I realised the comment is simply wrong!
Merge pull request #39 from zlot/patch-1

Updated comment that gave incorrect information