argparse 2.0

[Andrey Zherikov]

This took much more than I expected but finally, I'm glad to 
announce that a new major version of 
[`argparse`](https://code.dlang.org/packages/argparse) is 
published.

This version contains a bunch of breaking changes as well as a 
bunch of enhancements and bug fixes. Most important is that it 
now follows [POSIX 
convention](https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap12.html) for command line tools by default. This eliminates the surprises for users who expects certain behavior from UNIX tools.

Please see all changes that went into this version 
[here](https://github.com/andrey-zherikov/argparse/releases/tag/v2.0.0)


Thanks to everyone who helped me with this - you made it possible 
and much better!