I shouldn't go this long without a commit again.

Unfortunately it was a bit too tangled together for me to figure out
how to commit piecemeal.
* Added an ideas section and an about section
* Gave projects a preview image
* Created _includes templates for the post/project previews
* Made some aesthetic changes to title layout and the post lists
* Moved a bit of less out of main.less, trying for a bit more encapsulation there.