updated styles
added symbols to logic and set theory
updated titles of binary relations and operations
Merge branch 'develop' into feat-37ent
added parens, brackets, braces, and lt/gt signs
added apos and quot, moved lt/gt to relations
moved quotes to new section
added some math symbols
reorganized groups
moved image to 'hosting' repo
fixed vru-top for siblings after :not(.H)
reordered properties
more logical heading subclasses
moved gutters to separate stylesheet
fixed siblings after headings
Merge branch 'fix-res-headings' into hotfix
Merge branch 'hotfix'

tag: v3.5.1
Merge branch 'master' into develop
fixed link to mathjax config
Merge branch 'hotfix' into develop