This will increase speed of compression and generate a smaller file, but not be backward compatible.
Tweak the way memory is allocated to optimise chances of success and minimise slowdown for the machine.
fsync to empty dirty data before allocating large ram to increase chance of mem allocation and decrease disk thrash of write vs read.
Add lots more information to verbose mode.
Lots of code tidying and minor tweaks.
Premalloc ram to improve early detection of being unable to allocate that much ram.
Make sure to always make chunk size a multiple of page size for mmap to work.
Begin changes to make variable byte width offsets in rzip chunks.
Decrease header entries to only 2 byte wide as per original rzip.
Random other tidying.
