Added open(…).read() and open(…).readlines(). Work around bug caused by Foundation not being available by caller.

Work around the following by exporting Foundation (@exported import Foundation):

Undefined symbols for architecture x86_64:
  "__TF10Foundation22_convertNSArrayToArrayU__FCSo7NSArrayGSaQ__", referenced from:
      _top_level_code in Pythonic-test-272a9b.o
Added Array.pop() and Array.pop(Int).