Made LogEntryWindow singleton and utf-8 improvment

Improved handling of utf-8 and made LogEntryWindow a singleton, so when
the user clicks the result-button, the one and only window is showing,
not a new window every time
Added confirm when closing window
Update logentrytable directly when pressing Log!

Made the LogEntryWindow "listen to" when the WeekLoggerWindow made it's
LogEntry