Switch to the *eww* buffer immediately to avoid doing it asynchronously

(eww): Pop to the *eww* buffer immediately after executing the
`M-x eww' command to avoid having buffers pop up later.
(eww-display-html): Don't pop the *eww* buffer.
(eww-display-raw): Ditto.
(eww-display-image): Ditto.
(eww-follow-link): Make going to #targets in the page work again.
Allow opening eww links in a new buffer

* net/eww.el (eww-browse-url): Optionally create new eww buffer.
(eww-follow-link): Follow in new buffer in case of prefix
argument, open externally with double prefix.
Fix bug marking