Major changes, including Brotli and Lizard

- update of zstd-mt library
- add brotli v0.6.0
- add lizard v2.0
- xxhash is from zstd for lz4, lz5 and lizard now
- update also the documentation, where needed

cleanup.cmd

@@ -2,6 +2,8 @@
 
 FOR /R .\ %%d IN (AMD64 O) DO rd /S /Q %%d 2>NUL
 
+del "CPP\7zip\*.7z" 2>NUL
+del "CPP\7zip\7z*.exe" 2>NUL
 rd /S /Q "CPP\7zip\bin32" 2>NUL
 rd /S /Q "CPP\7zip\bin64" 2>NUL
 rd /S /Q "CPP\7zip\codecs" 2>NUL