Removing old, currently never used code
Obsolete comments
Secondary nav: no <hr>/<span> allowed directly under <ul>
Put navigation styles into own sass file
Sassified and cleand up navigation styles
Split into _nav-pimary.scss and _nav-secondary.scss
Refactored/rewrite of navigation style (manly the secondary one)
Sorry for the big commit, but as it is more a rewrite as refactoring...
Some minor issues still in there
delete generated css
add generated css
Merge pull request #1579 from rarila/sidebar

 Refactoring of navigation (mainly the secondary one)
Small tweaks in sidebar.
introduce field manager preloaded with defaults
add default fields in constructor
fields is an object not an array
Bumping Foundation to 5.4.0
Added some new, random, header images.
Exception class for low level errors
Replace lowlevelError() calls with throwing exceptions
No global $app uses anymore, global functions can access $app via ResourceManager::getApp(). Early access attempt to $app throws LowlevelException
Merge branch 'master-org' into code-cleanup