Handle blank comment lines

These should be coming out as blank lines in the outputed markdown
Add to pollock blog post

This includes:
   - Switching the metre->pixel code to use the width of the canvas and
     the width of the space,
   - A whole bunch of writing
   - Switching starting-point to use map
   - Picking colours out of number 8 pallete and using them to render
Add links to clojuredocs in code snippets

This sed expression will find any keywords and convert them to links
that point to clojuredocs
Add more to the draft of this tutorial

I've finished a first pass of the Starting points and projection and
Splatter