Update to 7-Zip Version 21.04

- first test... no release!!!

DOC/7zip.wxs

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 
 <?define VerMajor = "21" ?>
-<?define VerMinor = "03" ?>
+<?define VerMinor = "04" ?>
 <?define VerBuild = "00" ?>
 <?define MmVer = "$(var.VerMajor).$(var.VerMinor)" ?>
 <?define MmHex = "$(var.VerMajor)$(var.VerMinor)" ?>

DOC/readme.txt

@@ -1,4 +1,4 @@
-7-Zip 21.03 Sources
+7-Zip 21.04 Sources
 -------------------
 
 7-Zip is a file archiver for Windows. 

DOC/src-history.txt

@@ -1,6 +1,21 @@
 HISTORY of the 7-Zip source code
 --------------------------------
 
+21.04 beta     2021-11-02
+-------------------------
+- 7-Zip now reduces the number of working CPU threads for compression,
+  if RAM size is not enough for compression with big LZMA2 dictionary.
+- 7-Zip now can create and check "file.sha256" and "file.sha1" text files 
+  that contain the list of file names and SHA-1 / SHA-256 checksums in format 
+  compatible with sha1sum/sha256sum programs.
+
+
+21.03 beta     2021-07-20
+-------------------------
+- The maximum dictionary size for LZMA/LZMA2 compressing was increased to 4 GB (3840 MiB).
+- Minor speed optimizations in LZMA/LZMA2 compressing.
+
+
 21.02 alpha    2021-05-06
 -------------------------
 - 7-Zip now writes additional field for filename in UTF-8 encoding to zip archives.