This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
or edited some other way to fix the grammar.

  two makefile macros SHLIB_SUFFIX and EXT_SUFFIX. SO now has the value of
  SHLIB_SUFFIX again (as in 2.x and 3.1). The SO macro is removed in 3.4.

Revert r88272 -- the examples are more readable with spacing.
Add todos for difflib and logging.