Bugfixes in DataInputImpl and record id decoding. These fixes are related to confusion about whether the position is relative to the "view" of the data input on the underlying byte[] or absolute on the underlying byte[]. From now on, it is relative and the absolute position is defined by the "startPosition" field initialized at construction time.

This came up because with hbase 0.94.6 the buffers used in filterRowKey are no longer always zero-based, so it seems.