DOC: use rst not md in for numpy debug error link

Also retry "apt-get update" in travis if "apt-get install" fails, because that was probably the reason.

Try to stabilise a test that depends on importing from the current directory right after creating a module there.

Adding tests for "pure python mode" part 13

Removing the reference guide from the docs.

Gradually enabling PEP8 checks on Travis ci.

Moved the Cythonize section in the userguide.

Moving the compiler options into the source files and compilation.

Moving Integrating multiple modules and Distributing cython modules into the userguide.

Added the pep8 test to travis. All the warnings are disabled and only a few error checks are enabled.

Improve C++11 containers

Type annotation pyi file and tests (II)

Added a make.bat to be able to build the docs on Windows too.

Disable failing OpenMP tests in Py3.4 on MSVC, probably an old compiler version on appveyor (and I don't feel like fixing it before Py3.4 goes EoL).
Closes #2489.

Closes #2489.

Moving compilation from the reference guide to the userguide Part 4

Add NPY_CASTING

Add `typeobj` to `dtype`