Remove unused option "exclude_useless_cards"

Usefulness of cards depends on situations.  So that it's not
a computable aspect.  Additionally, useless cards still have a power to
change flows of games by occuping stacks of the random market.
Therefore, this option is useless.

Since this option is not implemented and its UI is disabled,
it's safe to remove this option.

Close gh-47.
Remove unused option "include_pairs"

"include_pairs" is hard to compute.  How to deal with many attack cards
without defense cards is also a part of this game.  In addition, recent
expansions have no defense card.  It implies that new defense cards will
almost never be designed.

This option is not implemented and its UI is disabled.
So that it's safe to remove this option.

Close gh-48.
Merge branch 'remove-unused-options'
Update for the 2nd preview of Six-Cities Alliance

Source: http://hatokura.flipflops.jp/wordpress/archives/931
Merge branch 'update-for-second-preview-of-six-cities-alliance'