experimental support for querying the type of expressions within macros

normalised the line endings of macros.nim (minor edits otherwise)

tests/compile/tmacrotypes.nim

@@ -0,0 +1,12 @@
+import macros, typetraits
+
+macro checkType(ex, expected: expr): stmt {.immediate.} =
+  var t = ex.typ
+  assert t.name == expected.strVal
+
+proc voidProc = echo "hello"
+proc intProc(a, b): int = 10
+
+checkType(voidProc(), "void")
+checkType(intProc(10, 20.0), "int")
+checkType(noproc(10, 20.0), "Error Type")