Add more tests for edge-case macro and interpolation expansion behavior

Fixes #1803

test/asm/delayed-interpolation.asm

@@ -0,0 +1,32 @@
+DEF SLIME_HP  EQU 35
+DEF SLIME_ATK EQU 15
+DEF SLIME_DEF EQU 26
+DEF MIMIC_HP  EQU 20
+DEF MIMIC_ATK EQU 21
+DEF MIMIC_DEF EQU 28
+
+MACRO with_each
+	for i, 1, _NARG
+		REDEF temp EQUS STRRPL(\<_NARG>, "?", "\<i>")
+		{temp}
+	endr
+ENDM
+
+DEF with_each_stat EQUS "with_each HP, ATK, DEF,"
+
+with_each_stat """
+	println STRFMT("Average ? is %d", (SLIME_? + MIMIC_?) / 2)
+"""
+
+MACRO buff_monster
+	REDEF monster EQUS STRUPR(STRSLICE("\1", 0, 1)) ++ STRLWR(STRSLICE("\1", 1))
+	; delayed \{interpolation\} is necessary here
+	; escaping the '}' is not essential (same as '>' in HTML)
+	with_each_stat """
+		DEF buffed = \1_? * 120 / 100
+		println "{monster}'s ? went from \{d:\1_?\} to \{d:buffed}!"
+	"""
+ENDM
+
+buff_monster MIMIC
+buff_monster SLIME