angles: improve some variable names and comments.

date_and_time/jd2ymdhms(): use floor() iso int().

getopt / getopt_get_command_argument(): arg: retval -> param in Doxygen.

Few more copyright updates.

constants/set_SUFR_constants_environment(): use tmpStr*(999)

* constants/set_SUFR_constants_environment(): use tmpStr*(999):
  * iso tmpStr*(99)
  * to match environment-variable strings

Add SUFR_getopt: command-parameter parsing similar to GlibC's getopt

* Add SUFR_getopt: command-parameter parsing similar to GlibC's getopt:
  * function getopt(): parse short command-line options (e.g. -f file.txt)
  * function getopt_long(): parse short or long command-line options (e.g. --file file.txt)
  * subroutine getopt_help(): print available short options for getopt()
  * subroutine getopt_long_help(): print available short and/or long options for getopt_long()

Updated copyright to 2016

CMake: install man/ in (/usr)/share/man/, since man pages are now in …

…man/man3/ and man/man3f/

print_commandline_options_values(): added Doxygen descriptions

Trivial update