PyFloat_FromString. (fixes bug #1650903)

The compiler package hasn't been updated yet; test_compiler.py fails.
Otherwise all tests seem to be passing now.  There are no occurrences
of __metaclass__ left in the standard library.
Docs have not been updated.

_seekable.

Daniel Stutzbach (already in) is main author of _fileio.c.

Add a missing forward declaration for PyFileIO_Type. The _fileio module now compiles with --with-pydebug.

to the cowboy way they are currently hacked in).

(see SF#1671314) with small tweaks.
The io module now uses this instead of its own implementation
of the FileIO class, if it can import _fileio.

the amount of data read.

I cleaned up whitespace but otherwise didn't change it.

This will need work to reflect the tentative decision to drop nonblocking I/O
support from the buffering layers.

This fixes test_compiler, test_transformer, and test_parser.

Fix by Pete Shinners (for his own bug :-).

Also implemented Neal's suggestion (add fileno() to SocketIO)
and some unrelated changes, e.g. remove Google copyright
and make BytesIO a subclass of BufferedIOBase.

Add nonlocal_stmt to Grammar and Nonlocal node to AST.  They both
parallel the definitions for globals.  The symbol table treats
variables declared as nonlocal just like variables that are free
implicitly.

This change is missing the language spec changes, but makes some
decisions about what the spec should say via the unittests.  The PEP
is silent on a number of decisions, so we should review those before
claiming that nonlocal is complete.

Thomas Wouters made the grammer and ast changes.  Jeremy Hylton added
the symbol table changes and the tests.  Pete Shinners and Neal
Norwitz helped review the code.

Remove duplicate refs to int from int/long unification presumably.  (There might be more refs like these.)