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.
diff --git a/py/objbool.c b/py/objbool.c
index 2dd019b..1dc5e57 100644
--- a/py/objbool.c
+++ b/py/objbool.c
@@ -29,7 +29,7 @@
     switch (n_args) {
         case 0: return mp_const_false;
         case 1: if (rt_is_true(args[0])) { return mp_const_true; } else { return mp_const_false; }
-        default: nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_TypeError, "bool takes at most 1 argument, %d given", n_args));
+        default: nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "bool takes at most 1 argument, %d given", n_args));
     }
 }
 
@@ -46,7 +46,7 @@
 }
 
 const mp_obj_type_t bool_type = {
-    { &mp_const_type },
+    { &mp_type_type },
     .name = MP_QSTR_bool,
     .print = bool_print,
     .make_new = bool_make_new,