this allows cmd_push_button_new_tab to open the new tab right *after* the current one, instead that always at the end.

the reload command doesn't push the current url to the history anymore.

and while there also rename the bogus completing_read to minibuffer_read. To get a ``completing-read'' one has to call enter_minibuffer with the right parameters.

in order to do so, we also have to export some internal variables from ui (the width and height of the window). Not the best possible outcome, but are used only in recompute_help, and can be dropped later. Also, move wrap_page to wrap.c.

don't load all the tabs when starting up, only the current one. Defer the loading of the others when switching to them.