COMPAT: From the next release PyPy fixed tp_basicsize of PyType_Type

Closes #2152.

Made other readmes pretty for github.

Added a note for Cython for numpy users.

Infer bytes/str type for safe bytes/str %-formatting cases that never returns Unicode strings in Py2.
Closes #2153.

An improved version of the tutorial.

Misc. typos

Found via `codespell`

Closes #2157.

See #2148.

Remove Greg's email address from the Cython readme front page as he's really not the right person to contact anymore (and it's still directly available from the Pyrex homepage that we link to).

Made the readme pretty for github.

Fix one word typo

changes the text "may or be not be" to "may or may not be"

Made the print python 3 style. pep8 and link to memoryviews.

Updated cythonize.

Put the pip installation first.

Improvements of the docs.

Split prototype part off a utility function to move the actual implementation to the end of the C file.