Removed caller from tx and added "callership" to account.

Transactions can no longer serve as callers. Accounts are now the
initial callee of closures. Transactions now serve as transport to call
closures.

ethchain/transaction.go

@@ -29,15 +29,6 @@ func NewTransaction(to []byte, value *big.Int, data []string) *Transaction {
 	return &tx
 }
 
-// Implements Callee
-func (tx *Transaction) ReturnGas(value *big.Int, state *State) {
-	// Return the value back to the sender
-	sender := tx.Sender()
-	account := state.GetAccount(sender)
-	account.AddFunds(value)
-	state.UpdateAccount(sender, account)
-}
-
 // XXX Deprecated
 func NewTransactionFromData(data []byte) *Transaction {
 	return NewTransactionFromBytes(data)