Some minor changes in source structure

Actually, the only changes are file-permissions for source code, even for the Perl, test modules.  Although they could be executed from the shell, since they are just Perl scripts, yet it's not declared so with a shebang (#!/usr/bin/env perl, for example) and the shell mistakenly executes them as shell scripts.

If someone would wish to execute them directly as programs, then the proper shebang declaration should be on the head of the files.