moved all images into a single buffer (no more saving vector+display vector) the images are now put into a single buffer thats divided into batches; when saving data every completed batch is saved removed several instances where data has been copied multiple times in memory; now, all incoming data from the API is alwas written into the same, previously reserved memory

Signed-off-by: Franz Sattler <sattler@ad.dkfz-heidelberg.de>