Add a typeName() method to each type for error printing purposes.

Test: compiles with mma
Change-Id: I1283c395440282fde1106ad47aa185bdeda75880
diff --git a/ScalarType.cpp b/ScalarType.cpp
index 0e4beaf..a60215a 100644
--- a/ScalarType.cpp
+++ b/ScalarType.cpp
@@ -37,6 +37,10 @@
     // do nothing
 }
 
+std::string ScalarType::typeName() const {
+    return getCppStackType();
+}
+
 std::string ScalarType::getCppType(StorageMode, bool) const {
     static const char *const kName[] = {
         "bool",