Python 3: more native imports and modules

[josephsl]

Link to issue number:

None

Summary of the issue:

There are more modules that could see Python 3 native import.

Description of how this pull request fixes the issue:

Deferred from @michaelDCurran's native imports work:

1. cPickle -> pickle
2. Python console: builtin -> builtins, resolving things such as obtaining debug flag via Python Console.

Steps:

1. Grep -r "__builtin" source and grep -r "cPickle", as well as others.
2. Edit the source code as appropriate.

Testing performed:

Tested with both Python 2 and 3 versions of NVDA, along with Python interpreters.

Known issues with pull request:

None

Change log entry:

None

Additional context:

There might be more modules that are not seeing Python 3 native imports. Also, there might be modules that are imported but are not used at all e.g. io.StringIO is imported from config main module but isn't used.