CSS float support

This is a feature request.

It would be awesome to have CSS `float` support. Reference: http://www.w3.org/wiki/CSS/Properties/float

Float would increase the renderer versatility. At the moment aligning element left and right is quite a hustle.

The issue names no source file, test, or renderer entry point; start by locating the existing element-alignment and layout handling, then compare it with the linked CSS float reference. Define supported left and right float behavior and add focused coverage before considering the work done.

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