Calculate topbar distance on window resize

If a element of the page is resized on window, distance must be
recalculated when sticky is enabled
Top bar link hover background color was being ignored due to small SCSS error. This fix causes the hover link color and background variables to be respected since they're being applied in the correct selector.
Added SCSS for Top Bar to degrade gracefully when Javascript is disabled.

When Javascript is disabled, allows dropdowns to appear on hover, and
also allows top bar menu items' background and font color to change on
hover.
Reset content width and height in mobile
Re-organized pagination code to support user-defined class names for all elements
Do not set the global li font color - less flexible than controlling on a per-selector basis
Added Silverstripe theme to Readme
Removed unnecessary whitespace from Readme
Fixed typo on Javascript page
fixed typo on thumbnail page in the mixin section
Merge pull request #2481 from aparis/topbar-window-resize

Calculate topbar distance on window resize
Merge pull request #2483 from prembo/master

Fix enabling top bar link & background colours (set via variables in _settings.scss) to have effect
Merge pull request #2543 from mmikitka/section_reset_vertical_tabs_height_and_width

Reset content width and height in mobile
Merge branch 'pagination_reorganization' of github.com:mmikitka/foundation into mmikitka-pagination_reorganization
updated pagination comments
update
Merge pull request #2571 from mmikitka/remove_default_breadcrumb_color

Breadcrumbs: Do not set the global li font color
Update foundation.topbar.js

on scroll, fixed class was never removed.
changed comparison from distance

All credits to iamjonatha see issue #2564