Changes in version 1.21:

The last argument of the C++ constructor and of the C function 'ap_init' has
been changed from 'bool in_order' to 'int flags'. This change is
backwards-compatible after recompilation because the default value of both
arguments is 0, and the new flag 'in_order' has a value of 1. So the old
'in_order = true' is equivalent to the new 'flags = in_order'.

The C++ constructor and the C function 'ap_init' have been extended with the
flag 'in_order_stop' to parse the first non-option argument and all the
arguments following it as non-option arguments, even if they begin with a
hyphen. This is similar to the POSIX function 'getopt', which stops option
processing after finding the first non-option argument.

The C++ constructor and the C function 'ap_init' have been extended with the
flag 'in_order_skip' to parse only the heading options, skipping the first
non-option argument and all the arguments following it. This mode is useful
for parsing the command line of programs that invoke other programs, like
'timeout', 'xargs', or 'valgrind'.

The C++ constructor and the C function 'ap_init' have been extended with the
flag 'neg_non_opt' to parse negative numbers as non-option arguments without
reordering them. This mode is useful for parsing the command line of tools
like 'seq' which take negative numbers as arguments. (Suggested by Mohammad
Akhlaghi):

    $ arg_parser +15 -Inf 0 -20 -a -.5 -v
    option '-a'
    option '-v'
    non-option argument '+15'
    non-option argument '-Inf'
    non-option argument '0'
    non-option argument '-20'
    non-option argument '-.5'

The 'enum Has_arg' value 'yme' has been renamed to 'yesme'.

The code of the C version has been reorganized.

The new section 'Differences with getopt and getopt_long' has been added to
the manual.
