* Ignore mode, not all applications need to load everything (mapping tool no airports)
* removed signal in airport reader which is already in base class
* added "virtual" keyword
* fixed another syncronize typo
* added allDbEntiiesUsed() to also reflect the config (ignore flag)
* ensure allSwiftDbData are signaled correctly even with ignore flag
* do not init shared URLs before needed
* do not load info objects when DB is unavailable
* adjust reader flags when DB is down
* airport URL available in setup
(applied after 1st performance fix for cache was ready)
* utility functions to detect if only caches are used
* renamed some functions
* renamed some db flags and added new ones