Implement proper exception type hierarchy.

Each built-in exception is now a type, with base type BaseException.
C exceptions are created by passing a pointer to the exception type to
make an instance of.  When raising an exception from the VM, an
instance is created automatically if an exception type is raised (as
opposed to an exception instance).

Exception matching (RT_BINARY_OP_EXCEPTION_MATCH) is now proper.

Handling of parse error changed to match new exceptions.

mp_const_type renamed to mp_type_type for consistency.

py/objcomplex.c

@@ -66,7 +66,7 @@ STATIC mp_obj_t complex_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const
         }
 
         default:
-            nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_TypeError, "complex takes at most 2 arguments, %d given", n_args));
+            nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "complex takes at most 2 arguments, %d given", n_args));
     }
 }
 
@@ -86,7 +86,7 @@ STATIC mp_obj_t complex_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 }
 
 const mp_obj_type_t complex_type = {
-    { &mp_const_type },
+    { &mp_type_type },
     .name = MP_QSTR_complex,
     .print = complex_print,
     .make_new = complex_make_new,