Unicode support and adding user by SID

[WicRus]

Simple realisation supporting unicode by unicode-c.
Adding users by SID, important for AD users, who cannot be added by RID.
Fixed 3 cast type warnings.

[adrian15]

Thank you @WicRus .

1. This is not upstream for chntpw.
   Upstream for chntpw can be found at: https://pogostick.net/~pnh/ntpasswd/ .
   So you might want to send your improvements there instead.

2. I might fork chntpw into a new program on its own soon.
   If you want your changes included there you should rebase your pull request to this branch: https://github.com/rescatux/chntpw/tree/chntpw-ng-1.01 .

That way we can discuss the several bugs you have in your code.

[WicRus]

Replaced to Chntpw ng 1.01