GNU automake and autoconf for building, argp for arguments.

- I configured EllipticalMask to be built with GNU AutoConf and GNU
  AutoMake. It is much more versatile now and easier to configure for
  the future and on other machines.

- I changed the whole argument parsing method of EllipticalMask to use
  GNU libc's Argp parser instead of the POSIX getopt. It is much more
  stronger in parsing the arguments now and a very complete help
  message is printed.

- I removed the option to print statistics, because a separate program
  I wrote (FitsStats) will do that job.