added {unattach} cost

this can also be used for "equipped creature has unattach and blah" cards using 
auto=teach(creature) {unattach}:blah

also corrected a long standing guiupdating issue. a long long time ago a replace was removed from GuiPlay::Update in hopes to increase performance no amount of performance increase is worth having cards not updating thier position after an event recieve happens. this means curse will finally go to the correctly choosen players battlefield, equipment will no longer just linger after its target dies, auras won't stay on battlefield after a card is exiled. ect. no preformance decrease noticed, if anyone else notices one let me know.

projects/mtg/include/ExtraCost.h

@@ -142,6 +142,17 @@ public:
   virtual int doPay();
 };
 
+//unattach cost
+class unattachCost : public ExtraCost
+{
+public:
+    unattachCost(MTGCardInstance * realSource = NULL);
+    MTGCardInstance * rSource;
+    virtual int isPaymentSet();
+    virtual int canPay();
+    virtual int doPay();
+    virtual unattachCost * clone() const;
+};
 //tap  cost
 class TapCost : public ExtraCost
 {