Added new setting $showNumOfPreviouslyUsedIdPs to standalone and embedded WAYF. Shows last used n IdPs at top of drop-down list
Outsourced Embedded WAYF JS into own file
Logos are now also shown for IdPs from Discovery feed
Refactored some code

Improves fix for #2596

Fixed a language string for permanent settings

Added additional data protection feature that uses the referer to decide whether or not to preselect an Identity Provider in the Embedded WAYF
If the Discovery Feed feature is activated only those IdPs are shown that are contained in the feed. Others will be hidden automatically.
Added code to automatically set default proper values in case there are not defined in the configuration
Added improved drop-down feature with search as you type functionality
Added licenses of added libraries

Updated specific language instructions
Renamed some language strings

Removed access_target string because it is almost a duplicate of access_host 

Fixed #407