CSS layout class prefix

[ryanve]

In 1.0 I used l- as a prefix for layout modifiers (applyable via skins).

• .l-lheader - aligns <header role="banner"> to left
• .l-rmenu - floats .site-nav to right
• .l-rsidebar - floats .main-widget-area to right

l- is somewhat standard and terser than layout- but is it enough?