a few fixes for rare bugs/malfunctions

a few fixes for rare bugs/malfunctions
- AliHLTProcessor/AliHLTDataSource: setting the output size to zero by default
  if the high level component interface is used. This handles the case of a component
  using the high level interface, but not publishing an output block for a particular
  event -> PubSub relies on output size zero if no data has been written
- toolbox publisher components handle output size correctly
- AliHLTTask: increase headroom in the output buffer to allow small extra data blocks
  from the base class
- HLTOUT handler for kAliHLTDataTypeComponentTable added
- TPCEsdWriterComponent handles output size correctly for SOR/EOR events