Merge: contrib/header_static: a cog in the toolchains to generate Objcwrapper

### Filters preprocessed C-like header files to remove static code and keep their signatures.

This tool is used in the process of parsing header files to extract
information on the declared services (the functions and structures).
This information is then used to generate bindings for Nit code
to access these services.

The C header sometimes contains static code. It deletes static code of
headers, but keep their signatures. This tool is an extension of
header_keeper. It searches the keyword static to identify
the static code, and ignore the code into their brackets. The result is
printed to sdtout.

~~~sh
cat Pre-Processed/CGGeometry.h | header_static Pre-Processed/CGGeometry.h > Pre-Processed/static_header.h
~~~

This module can also be used as a library.
The main service is the method `header_static`

Pull-Request: #1396
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>