Rename QUI::getDataBase to QUI:getDatabase

There is a typo in the method name.
It's called database not data base, thus the method should be called getDatabase.

How to refactor:

1. introduce new method getDatabase that calls getDataBase
2. set method getDataBase as deprecated
3. introduce breaking change with the next major release:
   1. copy method body of getDataBase to getDatabase
   2. delete getDataBase method

/cc @henbug