add a diffractometer's template file for documentation

this file is also compiled during the build process to ensure that it
can be used by users to add a new diffractometer.
improve the template
fix the documentation

now the check target verify that the embeded python code is ok
export the pseudo_axes_names in the bindings
remove an inconsistancy between the C-API and the bindings.
prepare the NEWS file for the release
remove the embeded bullet library.

this will reduce the work for the packaging.
do not install the hkl3d.pc