Merge branch 'v2_6_1'

Dockerfile

README.md

pom.xml

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

...in/java/de/deadlocker8/budgetmaster/accounts/Account.java

...java/de/deadlocker8/budgetmaster/categories/Category.java

.../deadlocker8/budgetmaster/controller/AboutController.java

...e/deadlocker8/budgetmaster/database/BackupItemParser.java

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

.../deadlocker8/budgetmaster/database/DatabaseParser_v3.java

.../deadlocker8/budgetmaster/database/DatabaseParser_v4.java

.../deadlocker8/budgetmaster/database/DatabaseParser_v5.java

.../deadlocker8/budgetmaster/database/DatabaseParser_v6.java

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

...e/deadlocker8/budgetmaster/database/InternalDatabase.java

...eadlocker8/budgetmaster/database/legacy/LegacyParser.java

...java/de/deadlocker8/budgetmaster/database/legacy/Tag.java

...de/deadlocker8/budgetmaster/database/legacy/TagMatch.java

...adlocker8/budgetmaster/database/model/BackupDatabase.java

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