Further development/refinement of IsoSampleTableBox.remove_sample_refs_before_point()

Added chunk_index/bytes_/samples_into_chunks calculation for case where the
 sample offset is provided.

Added/re-added code for truncating the SampleSizeBox, ChunkOffsetBox, and
 SampleToChunkBox to the provided/calculated sample number.

Added diagnostic output for printing the SampleTableBox tables before/after
 doing the sample removals.

Consolidated IsoChunkLargeOffsetBox into IsoChunkOffsetBox. It now will
 read/write offsets according to the box type being read/written. Did this
 to centralize the offset logic.

Tested with just B-AVC_MP4_MP_SD-03.MP4 for the time-being.