#120 BillingKundeRenderer: removed the boolean variable editable
#120 changed appearance of the billing request. It now looks like a hyperlink.
#120 filter for geschaeftsbuchnummer now also supports wildcards and substrings
#120 write the result of the found billings
#120 changed column name from Preis to Preis (netto)
#120 BillingKundeRenderer.calculateTotalSumFromBillings() use BigDecimal and round to two decimal places
#120 added InformationDialog if the user unselects all Verwendungszwecke
#120 billings are fetched in a SwingWorker Thread, while the billings are fetched a JXBusyLable is shown
#120 added pseudo-user to ignore the user filter + jalopy