implement $EA7E entry point and fix $EA31 entry point. Issue #20

c64/kernal/ea7e.s

@@ -0,0 +1,11 @@
+	;; https://csdb.dk/forums/index.php?roomid=11&topicid=5776
+	;; Clear the CIA1 interrupt flag, and then fall through to
+	;; the return from interrupt routine
+
+clear_cia1_interrupt_flag_and_return_from_interrupt:
+
+	;; We have free choice of LDA, LDX or LDY to achieve this goal
+	;; in 3 bytes and minimum cycles. Thus we randomly choose LDY.
+	LDY $DC0D
+
+	;; FALL THROUGH to $EA81