Arg_parser 1.0

Arg_parser is an argument parser that follows POSIX and GNU conventions for command line arguments. Arg_parser is implemented as a C++ class, and is simpler, easier to use, and safer that "getopt_long".
Arg_parser does not modify its arguments, nor uses any global variables. So you may create more than one parser in your program if you need or want to. Arg_parser can also parse options from configuration files.
To use Arg_parser in your own programs simply copy the files "arg_parser.h" and "arg_parser.cc" in your sorce tree. See also the file "main.cc" for an example of use.
Enhancements:
- The license has been updated to GPL version 3 or later.