Add conventional Emacs ;;; documentation

Every Emacs plugin should end with ';;; {file} ends here' and
start with ';;; {file} --- description'. This comments adds
appropriate comments for emacs.el plugin.
Drop eshell requirement

We can use it from eshell without applying eshell/ prefix, so why
bother. And this prefix makes it inconvenient to call this function
via M-x.
Ignore emacs.fas and emacs.lib