Convert Python types to proper Python type hierarchy.

Now much more inline with how CPython does types.

py/objset.c

@@ -5,7 +5,9 @@
 #include "nlr.h"
 #include "misc.h"
 #include "mpconfig.h"
+#include "mpqstr.h"
 #include "obj.h"
+#include "runtime.h"
 #include "map.h"
 
 typedef struct _mp_obj_set_t {
@@ -29,10 +31,34 @@ void set_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj
     print(env, "}");
 }
 
-static const mp_obj_type_t set_type = {
+static mp_obj_t set_make_new(mp_obj_t type_in, int n_args, const mp_obj_t *args) {
+    switch (n_args) {
+        case 0:
+            // return a new, empty set
+            return mp_obj_new_set(0, NULL);
+
+        case 1:
+        {
+            // 1 argument, an iterable from which we make a new set
+            mp_obj_t set = mp_obj_new_set(0, NULL);
+            mp_obj_t iterable = rt_getiter(args[0]);
+            mp_obj_t item;
+            while ((item = rt_iternext(iterable)) != mp_const_stop_iteration) {
+                mp_obj_set_store(set, item);
+            }
+            return set;
+        }
+
+        default:
+            nlr_jump(mp_obj_new_exception_msg_1_arg(MP_QSTR_TypeError, "set takes at most 1 argument, %d given", (void*)(machine_int_t)n_args));
+    }
+}
+
+const mp_obj_type_t set_type = {
     { &mp_const_type },
     "set",
     set_print, // print
+    set_make_new, // make_new
     NULL, // call_n
     NULL, // unary_op
     NULL, // binary_op