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

Fixes #1803

test/asm/blue-paint-limits.asm

@@ -0,0 +1,43 @@
+macro outer_interp
+  def s equs "macro inner_interp\1\nprintln \"interp: \1 and \\1\"\nendm"
+  {s}
+  purge s
+endm
+; this prints "1 and red" and "2 and blue"...
+outer_interp 1
+inner_interp1 red
+outer_interp 2
+inner_interp2 blue
+
+macro do
+  \#
+endm
+macro outer_mac
+  do macro inner_mac\1\nprintln "mac: \1 and \\1"\nendm
+endm
+; ...but this prints "1 and \1" and "2 and \1"
+outer_mac 1
+inner_mac1 red
+outer_mac 2
+inner_mac2 blue
+
+macro outer_concat
+  do macro inner_concat\1\nprintln "concat: \1 and "++\\1\nendm
+endm
+; this does print "1 and red" and "2 and blue" though
+outer_concat 1
+inner_concat1 "red"
+outer_concat 2
+inner_concat2 "blue"
+
+macro simple
+  println "(\1)"
+endm
+; this prints """("\\1")""", not """("\1")"""
+simple "\\1"
+
+macro nth
+  println \1
+endm
+; this does not print "lol", it's an error
+nth \\2, lol