Merge pull request #92 from oerpub/semantics-drag-below-fold-57739880

let semantic blocks scroll with content (Aloha-Editor half)
Merge pull request #93 from oerpub/empty-math-breakage

Fix infinite recursion bug on tooltip/popover.
make the "copy section" same/styling as other "copy [element]"s
Merge branch 'refs/heads/improve-header-styling-58912428' into testing
Merge branch 'testing' of https://github.com/oerpub/Aloha-Editor into testing