py: Add support for float/double arrays in array module.

Addresses issue #981.

tests/float/float_array.py

@@ -0,0 +1,14 @@
+from array import array
+
+def test(a):
+    print(a)
+    a.append(1.2)
+    print(len(a), '%.3f' % a[0])
+    a.append(1)
+    a.append(False)
+    print(len(a), '%.3f %.3f' % (a[1], a[2]))
+    a[-1] = 3.45
+    print('%.3f' % a[-1])
+
+test(array('f'))
+test(array('d'))