fix Duel.GetFieldGroupCount

[salix5]

Problem

Duel.GetFieldGroupCount(tp,LOCATION_SZONE+LOCATION_FZONE,0)
It will count the same card twice.
If A has 1 Field Spell and 1 Continuous Spell:
Correct: 2
Now: 3

Reason

Duel.GetFieldGroup(tp,LOCATION_SZONE+LOCATION_FZONE,0)
It will put the cards in a set.

Duel.GetFieldGroupCount(tp,LOCATION_SZONE+LOCATION_FZONE,0)
It will not put the cards in a set.

Solution

use set in filter_matching_card, filter_field_card

Test

Add the following to the operation function of any Continuous Spell X:

Debug.Message(Duel.GetFieldGroupCount(tp,LOCATION_SZONE+LOCATION_FZONE,0))
Debug.Message(Duel.IsExistingMatchingCard(nil,tp,LOCATION_SZONE+LOCATION_FZONE,0,3,nil))

Activate a Field Spell
Acticate X

The result is

3
true

in current version.

@mercury233
@purerosefallen