Updated to latest WhatsAppApi dll
Added existing registration check

To prevent unwanted SMS messages in case you forgot your personal
password
Added tooltip for exist request button
Added tooltip for code request button

Also a small text change for exist button tooltip
Added command line version of exist request
Added build 1.6.0.0

- Added Code request button tooltip
- Added Exist request button:
WART only allowed you to use CodeRequest functionality for checking
registration details. If they matched up, you got a new password. If
they didn't, you got an SMS code.
I tend to forget my personal password so this was a bit impractical for
me. ExistRequest allows you to check registration details without
receiving an SMS when they mismatch.