* fixed several deprecation notices and warnings from MySQL8, most notably:
- SQL_CALC_FOUND_ROWS: stopped using DBSimple::selectPage and query 'SELECT COUNT(*) ...' separately where needed
- ON DUPLICATE KEY UPDATE ... VALUES(): use row alias for new values instead of VALUES function
- boolean shorthands to long form (&& -> AND, etc)
* fixed wrong indizes for gem color picker in locale 3 (deDE)
* fixed interpretation of filter enums. Some are providing their value directly, others have an intermediate key.
* createSQLForCriterium is no longer abstract. (was implemented in exactly the same way everywhere)
* erronous criteria are now logged and discarded entirely)
* vastly improved input validation
* content and type validation occurs when filter is created
* contextual filters like itemTypes are now only applied in context
* initial implementation
* this includes a complete reindexing of everything touching icons
* this also means, no linking to red-rocket-site though, they index them differently
