Drop support for Python 3.0 to 3.3

See #701.

Doc/Manual/Python.html

@@ -149,9 +149,9 @@
 
 <p>
 This chapter describes SWIG's support of Python.  SWIG is compatible
-with most recent Python versions (Python 2.7 and Python 3.x).  If you still
-need to generate bindings which work with older versions of Python, you'll have
-to use SWIG 3.0.x.
+with all recent Python versions (Python 2.7 and Python &gt;= 3.4).  If you
+still need to generate bindings which work with older versions of Python,
+you'll have to use SWIG 3.0.x.
 </p>
 
 <p>

Lib/python/builtin.swg

@@ -13,12 +13,9 @@ SWIGINTERN Py_hash_t
 SWIG_PyNumber_AsPyHash(PyObject *obj) {
   Py_hash_t result = -1;
 #if PY_VERSION_HEX < 0x03020000
-#if PY_VERSION_HEX < 0x03000000
   if (PyInt_Check(obj))
     result = PyInt_AsLong(obj);
-  else
-#endif
-  if (PyLong_Check(obj))
+  else if (PyLong_Check(obj))
     result = PyLong_AsLong(obj);
 #else
   if (PyNumber_Check(obj))

Lib/python/pyinit.swg

@@ -329,16 +329,7 @@ SWIG_init(void) {
   PyObject *m, *d, *md;
 #if PY_VERSION_HEX >= 0x03000000
   static struct PyModuleDef SWIG_module = {
-# if PY_VERSION_HEX >= 0x03020000
     PyModuleDef_HEAD_INIT,
-# else
-    {
-      PyObject_HEAD_INIT(NULL)
-      NULL, /* m_init */
-      0,    /* m_index */
-      NULL, /* m_copy */
-    },
-# endif
     (char *) SWIG_name,
     NULL,
     -1,

Lib/python/pyrun.swg

@@ -11,6 +11,10 @@
 # error "This version of SWIG only supports Python >= 2.7"
 #endif
 
+#if PY_VERSION_HEX >= 0x03000000 && PY_VERSION_HEX < 0x03040000
+# error "This version of SWIG only supports Python 3 >= 3.4"
+#endif
+
 /* Common SWIG API */
 
 /* for raw pointers */

Lib/python/pystrings.swg

@@ -137,11 +137,7 @@ SWIG_FromCharPtrAndSize(const char* carray, size_t size)
 %#if defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
       return PyBytes_FromStringAndSize(carray, %numeric_cast(size, Py_ssize_t));
 %#else
-%#if PY_VERSION_HEX >= 0x03010000
       return PyUnicode_DecodeUTF8(carray, %numeric_cast(size, Py_ssize_t), "surrogateescape");
-%#else
-      return PyUnicode_FromStringAndSize(carray, %numeric_cast(size, Py_ssize_t));
-%#endif
 %#endif
 %#else
       return PyString_FromStringAndSize(carray, %numeric_cast(size, Py_ssize_t));