Show all unhandled host and services in a menu

Add the option to define custom renderers for menu items and implement renderers to
display all unhandled services and host in a badge in the navigation.

resolves #7114
Merge branch 'master' into feature/navigation-unhandled-badges-7114

Conflicts:
	library/Icinga/Web/Menu.php
Merge branch 'feature/navigation-unhandled-badges-7114'

resolves #7114
StatusSummaryQuery: reorganize, add new columns

refs #6993
show/contact: first attempt to restyle them

refs #7104
NotificationHistoryQuery: names instead of aliases

refs #7104
list/notifications: don't show contact...

...when showing notifications for a single contact, other cleanup.

refs #7104