[js] simplify cw.log implementation There's no need to rebuild and array and join its content, just call console.log with ``arguments``. The only trick is that console.log must be called on a console instance.

../../doc/book usr/share/doc/cubicweb-documentation
../../doc/html usr/share/doc/cubicweb-documentation
../../debian/cubicweb-doc usr/share/doc-base/cubicweb-doc