launch_editor() is declared in strbuf.h but defined in builtin-tag.c.
This patch moves launch_editor() into a new source file editor.c,
but keeps the declaration in strbuf.h.
Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
