M26: Fixing the event definition to compensate bug in MIMOSA raw data

With an unknown probability, the MIMOSA DAQ is not transmitting the correct two frames. Assuming frames t and t+1 are expected it can happen that frames t-1 and t are copied to disk. This causes an artificial inefficiency if no additional timing layer is used. To overcome this issue, the option pixelated_timing_layer is added. If set to false, this enlarges the frames to cover the full possible timestamp range. This reduces the available statistics by a rate dependent fraction (Typically 30-40%).