added support for 'var' Elements
added single guillemets delimiters
Merge branch 'develop' into feat#16-math
finalized css for `var` Elements.

TODO: move `var {}` from '_code.less' to '_text.less'
Merge branch 'develop' into feat#19-docs

Conflicts:
	core/styles/all.css
	core/styles/typo/_code.less
rearranged some css Objects in source
split '_text.less' into smaller files
removed '.S' objects