Adresses #1471 - Extracted settings into settings variable. Reduced code.
Adresses #1471 - Fixed reference error, reduced code.
Adresses #1471 - Implemented category filter.
Adresses #1471 - Introduced SearchableMarkerCollection, reduced code accordingly.
Adresses #1471 - Removed drawTerminals(), drawMensen() and drawInstitutes(), replaced them with drawCategory().
Closes #1471 - Refactored and reduced code.
Merge branch '1471-sitemap-filter'