Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/benchmark/for.py

@@ -0,0 +1,20 @@
+from __future__ import print_function
+
+import time
+
+# Map "range" to an efficient range in both Python 2 and 3.
+try:
+    range = xrange
+except NameError:
+    pass
+
+start = time.clock()
+list = []
+for i in range(0, 1000000):
+  list.append(i)
+
+sum = 0
+for i in list:
+  sum += i
+print(sum)
+print("elapsed: " + str(time.clock() - start))