Now the attack target can be null. (for c93599951)

1. Now cards sp_summoned by Duel.SpecialSummonStep() will not be counted
into cards on the filed in every script function.

2. If a card fails to return to field, it should be sent to grave by
REASON_RULE.

change priority of loading scripts

This reverts commit 7058e371.

Now a player can remove 2^16-1=65535 counters from each card.

http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=14083&keyword=&tag=-1
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=12625&keyword=&tag=-1
Now negate/disable activation effects can be activated after effects
cannot be negated/disabled, and nothing will happen in resolution.

The condition inside ocgcore is moved to check_chain_negate(),
check_chain_disable().

Duel.CheckTribute()
Now it will check if there exist min<=i<=max such that releasing i tributes is possible.
(Note that relaesing k tributes is different from releasing k monsters,
since some monsters can be treated as 2 or more monsters)
The proof of correctness is shown below.

field::get_summon_release_exlist()
This function is just a support function of check_tribute(), and now it will not modify release_param.

card::is_can_be_summoned()
The aegument peffect is a special case used by effects that change theordinary summon procedure (c80921533),
and now it is seperated from normal cases.

TODO:
check min_tribute in scripts
Duel.CheckTribute(c,k,k)

TODO:
Add
e1:SetValue(SUMMON_TYPE_ADVANCE+k)
Duel.CheckTribute(c,k)
in EFFECT_SUMMON_PROC, EFFECT_LIMIT_SUMMON_PROC, EFFECT_SET_PROC, EFFECT_LIMIT_SET_PROC scripts

This reverts commit 573b7589.
This is a slightly revised version.