add ability to log errors to server and to add a js-stacktrace to the serverlog
enable to show serverside errors to the client as error of MessageBox.js
include handling of possible raceconditions on completeEdit, so that they do not lead to saving of the segment.Show sense-making messages to the user
removing of not needed and commented out console.log-calls
merge von sourceEditing-Feature
finish of racecondition-handling