incorporated MJ's suggestions:

incorporated MJ's suggestions:
- flush_copy_command() exploits fast unaligned memory access and memcpy()
lizard_compress():
- the test in_start==copy_start replaced by flag bof, in_start deleted
- if (copy_len > 0) replaced by if (copy_len)
- pos_bit |= 1<<4
- deleted testing cropping at BOF, it is obsolete now
lizard_decompress():
- at label perform_copy_command, we set expect_copy_command=2
- exploit fast unaligned memory access