Refactor to use FeeHandler function

types/account.go

@@ -48,8 +48,6 @@ type AccountMapper interface {
 	NewAccountWithAddress(ctx Context, addr Address) Account
 	GetAccount(ctx Context, addr Address) Account
 	SetAccount(ctx Context, acc Account)
-	GetFeePool(ctx Context) Coins
-	SetFeePool(ctx Context, coins Coins)
 }
 
 // AccountDecoder unmarshals account bytes

types/handler.go

@@ -3,5 +3,8 @@ package types
 // core function variable which application runs for transactions
 type Handler func(ctx Context, msg Msg) Result
 
+// core function variable which application runs to handle fees
+type FeeHandler func(ctx Context, fee Coins)
+
 // If newCtx.IsZero(), ctx is used instead.
 type AnteHandler func(ctx Context, tx Tx) (newCtx Context, result Result, abort bool)