Add .gitignore
Add documentation text file.

Add enumerated types documentation URL.
Makes sense to stay clear of Strings and Int for playing card
attributes.
Add enumerated types Rank and Suit.

Add enumerated types Rank.java and Suit.java in /src/
Prefer use of enums when playing cards.

Because the oracle javadocs tutorials says so.
Add class Card.

Add class Card, describing a playing card.
Class Cards left as it once was.
Merge remote-tracking branch 'origin/master'