implemented various task features:

- saving on CTRL+S
- editing of
    - start date
    - due date
    - members

project/src/main/java/de/srsoftware/umbrella/project/ProjectModule.java

@@ -43,7 +43,7 @@ public class ProjectModule extends BaseHandler implements ProjectService {
 		var user = users.loadUser(userId);
 		var member = new Member(user,READ_ONLY);
 		project.members().put(userId,member);
-		project.dirtyFields().add(MEMBERS);
+		project.dirty(MEMBERS);
 	}
 
 
@@ -190,7 +190,7 @@ public class ProjectModule extends BaseHandler implements ProjectService {
 				}
 			}
 			members.put(userId,new Member(users.loadUser(userId),permission));
-			project.dirtyFields().add(MEMBERS);
+			project.dirty(MEMBERS);
 		}
 	}
 

project/src/main/java/de/srsoftware/umbrella/project/SqliteDb.java

@@ -218,11 +218,11 @@ CREATE TABLE IF NOT EXISTS {0} ( {1} VARCHAR(255) PRIMARY KEY, {2} VARCHAR(255)
 				}
 			} else { // Update
 				try {
-					if (prj.dirtyFields().contains(MEMBERS)){
+					if (prj.isDirty(MEMBERS)){
 						var query = replaceInto(TABLE_PROJECT_USERS,PROJECT_ID,USER_ID,PERMISSIONS);
 						for (var member : prj.members().entrySet()) query.values(prj.id(),member.getKey(),member.getValue().permission().code());
 						query.execute(db).close();
-						prj.dirtyFields().remove(MEMBERS);
+						prj.clean(MEMBERS);
 					}
 					if (prj.isDirty()){
 						update(TABLE_PROJECTS).set(NAME,DESCRIPTION,STATUS,COMPANY_ID,SHOW_CLOSED).where(ID,equal(prj.id())).prepare(db)