Create sample project for multi-column text kit
WIP on multi-column textkit demo

It's not quite there yet, but nearly :)
Fixes the rendering of the textviews

The delegate doesn't seem to be reliable (well, it doesn't do what I
expect), so we pre-calculate the required space and render them.
Tidying up the code a bit.
Completes multi-column textkit writeup
Merge branch 'days/21-multi-column-textkit'