move file descriptor redirecting to Cython.Utils package and use it as context manager in test runner

--HG--
extra : transplant_source : w%8C%DC%3BS%CE%B2%8AC%D2%14%D3%99%B9%E8Z%0F%983%AD

--HG--
extra : rebase_source : 4cc5a2b5b9044e06fca82d216aa5a3c919abf033

--HG--
extra : rebase_source : 4cc5a2b5b9044e06fca82d216aa5a3c919abf033

--HG--
extra : rebase_source : 4cc5a2b5b9044e06fca82d216aa5a3c919abf033

Directory with __init__.pyc file is a package dir

Consider a directory with __init__.pyc as a package directory.

line-highlight fix + pygments highlight

- if pygments is availlable, highlight

- when lines have no generated code, do not generate the subdiv and do not
  make clickable

- line number with correct number digit for alignment of code

- line that can be expanded with + in front

- use 0 margin top and bottom for code blocks

Add a div with cython class for embedding

This allow to reuse directly the body and embed it without having to
wrap it in the correct div and have the CSS apply to it.