Fix latent bug when calling algo deinit in decompression code
Reduce diff threshold for slightly greater delta encoding
Limit similar buffer size difference for less wasted diffing
Change zlib compression wrapper to use faster deflateReset mechanism
Reduce optimization level for Dedupe code, it goes faster
Restructure compression functions to take chunk flag as argument.
Add missing error flag printing in LZMA.
Only create enough threads as needed by chunk size and file size.
Minor cleanups and variable name changes.
