Finalizing improve startup time for fresh or rollback'd session
Finally fixed the long-sought InputStream reading bug from
TransferableGraphFileReader.InputChannel.read(ByteBuffer).
The ByteFileReader implementation expected the provided
ReadableByteChannel to always provide a full buffer of data unless EOF
was encountered and the InputChannel.read implementation was not taking
care of that.
Also added simpler utilities for reading TG's from files/InputStreams
directly using static TransferableGraphFileReader.read(File/InputStream)
methods.
PlatformUtil.readTG can now finally use TransferableGraphFileReader for
maximal performance.