Text file location and permissions cleanup

* Moved text files from repository root back into src/, replacing the moved
  files with symlinks.
* Brought back the /README from mudos-0.9.20 which was clobbered accidentally
  by the mudos-v20.22 commit.
* Removed duplicate "readme" file from src/packages/
* Fixed permissions (chmod -x) files that did not need the execute bit.