2021-06-04

Changes:

• New clang64 environment
• Installation or first startup after unpacking will no longer leave idle background processes around
• Installer:
  • "maintenancetool.exe" was renamed to "uninstall.exe" and its features reduced to just uninstallation. See #25
  • documentation added for silent installation: https://github.com/msys2/msys2-installer/tree/2021-06-04#cli-usage-examples