Target documentation for Python 3 usage

2 is dead, long live 3. Mainly turning print info a function
and urllib import fixes

Update README.rst for Pywikibot core

The new version ('core') is much more used and developed
than the previous one ('compat').

Force opening README.rst as utf-8 in Py3k

Causes issues if the locale is not set to utf-8

Tests were not correctly testing the situations without a table close.
Fixed tests and then fixed tokenizers for failing tests. Also refactored
pytokenizer to more closely match the ctokenizer by only holding the
`_parse` methods in the try blocks and no other code.

One-line fix

Add some table tests to increase coverage. Also reorder some tests.

Python 3.4 compiles C extensions with the
`-Werror=declaration-after-statement` flag that enforces C90 more
strictly than previous versions. Move all statements after declarations
to make sure this extension builds on 3.4.

For wiki syntax tables, add `wiki_style_separator` as an attribute
for the Tag node. Also reorder `closing_wiki_markup` property and tests
to match its place in the constructor.

Table tags no longer self-closing. Rows and cells now contain their
contents. Also refactored out an `emit_table_tag` method.
Note: this will require changes to the Tag node and possibly the builder,
those changes will be in the next commit.

Remove style test to properly implement implicit style closes later.

Self-closing wiki syntax tags have incorrectly ordered wiki syntax
and padding, fixed the ordering.

CTokenizer is completely implemented in this commit - it didn't
make much sense to me to split it up. All tests passing, memory test
shows no leaks on Linux.

For the C tokenizer, include `<stdint.h>` and use `uint64_t` instead
of `int` for context. Changes to tables mean that context can be
larger than 32 bits, and it is possible for `int` to only have 16
bits anyways (though this is very unlikely).

For C compatability, switch table cell end to return the stack.
Now context is kept by using `keep_context` when calling `self._pop()`.

Various changes to avoid returning tuples - working on the C tokenizer
made me realize this was a bad idea for compatability/similarity between
the two.

Fix problem in which invalid table attributes were being parsed
incorrectly. Added tests.

Fix problem in which fake table closes were causing a problem inside
cells. Changed inline table handling to fix this.

Padding now included on all wiki table cells. With wiki table cells
that include attributes, `wiki_markup` is also included (unchanged).

Make sure py tokenizer methods only call methods that have been declared
earlier. Not necessary but makes it much easier to maintain/write
the C tokenizer if methods are in the same order.