Tools for Repacking

[wrathma]

based on latest github/zstd-1.5.7 sources. needs thorough testing. use 1.5.7 to compress. examples -

> zstd_decompress.exe

 Experimental ZSTD Decompressor by SYMM

 usage: zstd_decompressor input output
 replace input and/or output with - to use stdin/stdout

> zstd_decompress.exe input.zst output.exe
output.exe : 126607283 bytes

zstd_decompress.exe - - < input.zst > output.exe
<stdin>: 126607283 bytes written

on benchmarks its almost 2x slower than the official zstd binary release (1.5mb). still it is fast with almost 350MBps decompression speed for 4GB uncompressed data on my test system (4c8t i3) on nvme.