Replace qsufsort with sais

based on sais-lite [https://sites.google.com/site/yuta256/sais]
Add threaded patch generation
Use base16 format for per file hash
Add arguments for threads, memory limit, and cache dir
Add error if memory limit is insufficient
Add binary diff cache
Add liblzma dependency
Add lzma iostreams filter
Change compression filter to lzma
Add C99 as a requirement to build
Add extra line after last help message
Support lzma as shared object if available
Remove BZ2 dependency
Set lzma compression to default level

TODO: Make that a parameter to deltagen