#598 - converter can convert in both directions

.../de/deadlocker8/budgetmaster/database/DatabaseParser.java

...de/deadlocker8/budgetmaster/database/model/Converter.java

...er8/budgetmaster/database/model/v5/BackupDatabase_v5.java

...ster/database/model/v5/converter/AccountConverter_v5.java

...ter/database/model/v5/converter/CategoryConverter_v5.java

...master/database/model/v5/converter/ChartConverter_v5.java

...master/database/model/v5/converter/ImageConverter_v5.java

...se/model/v5/converter/RepeatingEndOptionConverter_v5.java

...ase/model/v5/converter/RepeatingModifierConverter_v5.java

...abase/model/v5/converter/RepeatingOptionConverter_v5.java

...ter/database/model/v5/converter/TemplateConverter_v5.java

.../database/model/v5/converter/TransactionConverter_v5.java