changed subheadings and code blocks
updated table styles
cleaned up Less code on font families. TODO: modify font families and heading colors
changed heading colors
abstracted separated lines---use on footnotes (later)
updated TODO
finalized About page
modified heading vertical spacing
csslinted css

fallbacks, dupes, abstraction, units
slightly adjusted line height
cleaned '.fontsize-' interfaces
Merge branch 'rel-v3_1_3' into feat-fontsize

Conflicts:
	core/styles/_vert.less
	core/styles/all.css
compatibilified gradient Mixin
Merge branch 'rel-v3_1_3' into develop
Merge branch 'develop' into feat-doc

Conflicts:
	core/doc/grid.html
	core/doc/typo.html
	core/styles/all.css
	core/styles/typo/_code.less
updated style guide