Adding a simple and advanced mode

[hugolio]

The current Emnesøk interface has various features mainly useful for librarians (e.g.: showing vocabulary statistics, showing DDC classification codes). It would be good to add a dropdown menu to select a "simple" and "advanced" mode, the former aimed at end-users without experience with subject vocabularies, and the advanced mode aimed at librarians frequently working with the vocabularies.

Simple mode:
-Do not show vocabulary statistics by default
-Do not show DDC numbers in retrieved book lists
-Do not add link to subject terms from other vocabularies (since they lead to an error)
-Do not use certain terminology, e.g. "used for", "narrower", "broader" but create a simple representation.
-Remove "View concept in Skosmos" link
-Remove "starting with" / "containing" / ".." selector next to the search box, but select a default option

[hugolio]

Based on M. Wilson, Search User Interface Design (2011), design recommendation: "Avoid unnecessary information, which can be distracting during search."