#257 changed the message

The message shown in the warning error if the user input was wrong is
now more descriptive.
Merge branch 'feature/257-warning-message-in-Punktnummernreservierung' into dev
 #259 remove the AutoCompleteDecorator for the Auftraggeber-Combobox
Merge branch 'bug/259-quickfix-auftraggeber-combobox' into dev
fixed #261 dispose() didnt call unbind on the beansbindingGroup. Strong references were used too. This was causing the editor panel to never be destroyed by the garbage collector
Merge branch 'bug/261-memoryleak-baulasteditor' into dev
 #258 added a checkbox to BillingKundeAggregationRendere

Added a checkbox to BillingKundeAggregationRenderer, with which the user
can hide or show the abgerechnete billings. Also added the needed logic
for this checkbox.
Merge branch 'feature/258-Show-abgerechnete-billings-in-the-Kundengruppenrenderer' into dev
#246 created Sb_stadtbildserieAggregationRenderer Sb_stadtbildserieGridObject and Sb_stadtbildserieGridRenderer
#246 changes to load the images from a Serie
#246 make better use of the cache
#246 use priorityqueue in threadpool
#246 keep a reference to the last shown image in Sb_stadtbildserieGridObject
#246 added jgrid to pom
#246 moved the preview image panel from Sb_stadtbildserieEditor to an own class
#246 added the  Sb_stadtbildserieAggregationRendererInfoPanel to the Sb_stadtbildserieAggregationRendererSb_stadtbildserieAggregationRenderer
#246 the table in Sb_stadtbildserieAggregationRendererInfoPanel is refilled properly
#246 table: slight improvements
#246 jalopy
#246 modified the selection of the single statdbilder