Loading animation added, Right and Left panels separated (now they have different scrollbars), NavBar cleanup, Fixed navbar height problem when window width is less than 850 by hiding search field - Fixed requesting multiple pages when there is still one request processing, Fixed back button when it use history object of browser for doing its job, Fixed some forms not treated as ajax form, Fixed cross-panel refresh request, mCustomScrollbar added, Some minor css, javascript and html cleanups
Merge github.com:virtualmin/virtualmin-bootstrap-theme

Conflicts:
	index.html