first implementation: spell checking for zero hits

todo:
-   compare the spelling suggestions from SOLR with the created links on the surface (VuFind)
    -> especially compound spellings (I guess there is a mismatch)
- more code cleanup
- more documentation of dependencies between types defined in different modules (VuFindSearch / VuFind / SwissBib )

- write unit tests

- better configuration of default dictionaries

- ....

how to use it / short description of implementation:
- because we use spelling mechanism only in case of zero hits (VuFind creates them for every request if spellchecking is enabled which decreases performance if you don't use it) spellchecking should be set to false in config_base.ini
- the application by itself starts a second search only for spellchecking (without any facet and other not needed searchcomponents for spelling)
- we use the DirectSpellChecking (as a result we don't have to create a specialized index for spellings) but in the old "dictionary style way". This enables us to use part of the VuFind mechanisms for spellchecking - e.g. more then one dictionary. In contrast to the old VuFind dictionary style we have to perform the spellchecking queries sequentially because the spellchecking fields are defined with different analyzers in the SOLR Schema (this is not the case for the old dictionary style with dedicated spellchecking indexes for every single dictionary). Once the spellchecking queries are finished the spellchecking results have to be merged in order to use them in the view scripts
Merge branch 'development' into feature/spellchecking0hits

Conflicts:
	themes/swissbib/templates/search/results/content.phtml
solved!

conflict because of FRBR Handling and zero hits spellchecking in template
Merge branch 'development' into feature/spellchecking0hits
Merge branch 'development' into feature/spellchecking0hits
Merge branch 'development' into feature/spellchecking0hits