add call and ret function

add drop (idk if it is working right)
add prog5 and prog6

programs/prog5.asm

@@ -0,0 +1,35 @@
+//
+// prog01.asm -- call/ret without args, and without ret value
+//
+
+	asf	3
+	pushc	11
+	wrint
+	pushc	'\n'
+	wrchr
+	call	proc
+	pushc	44
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	halt
+
+proc:
+	asf	2
+	pushc	22
+	wrint
+	pushc	'\n'
+	wrchr
+	call	proctwo
+	rsf
+	ret
+
+proctwo:
+	asf	2
+	pushc	33
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	ret

programs/prog6.asm

@@ -0,0 +1,28 @@
+//
+// prog02.asm -- call/ret with args, but without ret value
+//
+
+	asf	3
+	pushc	11
+	pushc	33
+	call	proc
+	drop	2
+	rsf
+	halt
+
+proc:
+	asf	2
+	pushl	-4
+	wrint
+	pushc	'\n'
+	wrchr
+	pushc	22
+	wrint
+	pushc	'\n'
+	wrchr
+	pushl	-3
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	ret