Set <hr> margin difference to use rem-calc

As mentioned in #4549 foundation 5 replaces the need of em-calc and strip-unit functions in favor of rem-calc function.
Repeated buttonsize mixin
update change for 5.2.0
corrected z-index dialog modal
orbit should call start on timer restart event
Merge branch 'master' of github.com:zurb/foundation
don't require orbit links to be anchor tags
Makes me feel dirty, but this does solve a specificity / conflict issue
Added range slider variables to settings
Merge pull request #4622 from NikhilKalige/range-slider-variables

Added range slider variables to settings
Fix captions in Clearing viewer
Fixed the flex-video class for vimeo embeds
Fixing Forms in Tabs width issue
enable orbit vertical scrolling unless horizontal scrolling has crossed 5px threshold
Merge pull request #4561 from serglo/patch-1

Set <hr> margin difference to use rem-calc
Update deep linking documentation.
Trigger handler on tab content as well as tabs.
changed text in markdown example
update license copyright

Copyrights should be updated to the current year.
Merge pull request #4667 from jyek/fix-copyright-year

update license copyright