Makefile: updated L10N tasks to take into account the catalogs dedicated to the messages in Javascript files (#6353).
Also, added an `init-xy` target for creating the catalogs for a given locale `xy` (only create the missing catalogs, e.g. the new messages-js.po one).
Authored by: cboos 2010-05-24
Parent: [r9763]
Child: [r9765]
