Days 66 page related to doctests

For some doctests (hopefully few of them) tests are very long to run. For example, there is a dramatic

TestSuite(R).run(elements = [R.random_element() for i in range(3^6)])

In sage/rings/padics/padic_base_leaves.py

Plan of attack:

• run sage -t and sage -t --long on all Sage files

• sort the running time in decreasing order
• start the list from the begining, read the file and try to do faster tests