Release: Give more information in case PyPI upload validation fails.
MacOS: Support virtualenv to native Python installations too.

* The "Python/.." causes problems in this issue, normpath will
  remove it though.

* Not clear, why it was not an issue with Homebrew installations.
Standalone MacOS: Fix programs that use no shared libraries.

* Too simple programs end up using no DLLs, and then invoked
  install_name_tool without arguments, which raised an error.
New hotfix release.
Merge branch 'hotfix/0.5.4.2'