tests for inc/dec and deref

tests/run/unop_extras.pyx

+cimport cython
+
+def test_deref(int x):
+    """
+    >>> test_deref(3)
+    3
+    >>> test_deref(5)
+    5
+    """
+    cdef int* x_ptr = &x
+    return cython.dereference(x_ptr)
+
+def increment_decrement(int x):
+    """
+    >>> increment_decrement(10)
+    11 11 12
+    11 11 10
+    10
+    """
+    print cython.preincrement(x), cython.postincrement(x), x
+    print cython.predecrement(x), cython.postdecrement(x), x
+    return x