This release adds the ability to read additional arguments from file
and the ability to add sub-command under sub-command. The feature to
print candidates for unrecognized flags/commands was also added.
BaseArgumentParser interface was removed and the interface methods in
it were moved to ArgumentParser interface. All methods took
BaseArgumentParser now take ArgumentParser instead.
* If Subparsers.addParser() without prefixChars are called, subparser
inherits prefixChars from main parser.
* Added feature to read additional arguments from file. The set of
characters to prefix file path is set in ArgumentParsers factory
* The constructors of ArgumentParserException now take ArgumentParser
object as a parameter.
* Subparser interface now has addSubparsers() method. It means we can
add arbitrary number of sub-commands hierarchy.
* Removed BaseArgumentParser. All interfaces are moved to
* Added Subparsers.metavar(). By default, text to represent
sub-commands are concatenation of all sub-commands. This method can
override this default behavior and sets arbitrary string to
use. This is useful if there are many sub-commands and you don't
want to show them all.
* Use metavar if it is specified by user even if choice is specified.
In the previous implementation, choice's textualFormat() is used
over strings set by metavar(). Now strings set by metavar() has
precedence over choice.
* Added feature to print candidates for unrecognized flags/commands.
* Namespace: Added shortcut methods for byte, short, float and