[r-t] Challenge to produce new method - Double Helix Royal

[Mark Davies]

Super method, good work Rob. The PDF is big because it has the entire 
course, which makes the method look much scarier than it is (and it is 
quite scary enough already!). In order to see the entire blue line it's 
only necessary to have seven columns, not 21. Fortunately Boojum can 
trim it down for us - see attached (assuming it gets through).

MBD