Add new layouts

[aero31aero]

Add more layout options so that the editor adapts well to simpler/copmplex workflows:

Single page

A minimal UI so that only the editor is visible, and the user can focus on only the content.

Print View

Copy over CSS updates from original project so that printing is supported.

Noob Mode

Add a toolbar to help with markdown syntax. Not sure how this would work, but this deserves an attempt.

[aero31aero]

Reading Mode has problem. When you enter Read Mode and then the Split View gets enabled, then you cannot disable the whole Reading Mode thing. This is quite annoying since you cannot get back to editing the doc and the window goes empty with both the #in and #out hidden.