Add test case for some macro+interpolation behavior

test/asm/blue-paint.asm

@@ -0,0 +1,30 @@
+OPT r5
+
+DEF statement EQUS "println \"This is the song that never ends~\""
+
+; macro arguments are painted blue
+MACRO arg_to_arg
+	\1statement\2
+ENDM
+arg_to_arg \\3, \\4, \{, \}
+
+; ...but...
+MACRO arg_to_interp
+	\1statement\2
+ENDM
+arg_to_interp \{, \}
+
+; interpolations are not
+DEF open EQUS "\{"
+DEF close EQUS "\}"
+{open}statement{close}
+
+; which is why this halts
+MACRO endless
+	\1
+ENDM
+endless \\1
+
+; ...but this doesn't
+DEF infinite EQUS "\{infinite\}"
+{infinite}