big refactoring: cleanup

src/main/java/de/deadlocker8/budgetmaster/Main.java

...ocker8/budgetmaster/authentication/WebSecurityConfig.java

...de/deadlocker8/budgetmaster/database/DatabaseService.java

...ocker8/budgetmaster/repeating/endoption/RepeatingEnd.java

.../java/de/deadlocker8/budgetmaster/reports/ColumnType.java

...dlocker8/budgetmaster/reports/ReportGeneratorService.java

.../de/deadlocker8/budgetmaster/services/HelpersService.java

...a/de/deadlocker8/budgetmaster/services/ImportService.java

...ker8/budgetmaster/transactions/TransactionController.java

src/main/resources/templates/error/403.ftl

src/main/resources/templates/error/404.ftl

src/main/resources/templates/error/418.ftl

src/main/resources/templates/error/500.ftl

src/main/resources/templates/login.ftl