Arg_parser is an argument parser that follows POSIX and GNU conventions
for command line arguments. It is implemented as a C++ class, and is
simpler, easier to use, and safer that `getopt_long'.

For maximum stability, Arg_parser is self-contained. It extracts all the
information it needs from its arguments to avoid refering to them later.
This avoids index-out-of-bounds errors.

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.
