(ido-initial-position): New variable.

(ido-initial-position): New variable.
(ido-read-internal): Set it if default item is specified.
(ido-minibuffer-setup): Position cursor accordingly if set.
(ido-edit-input): C-e moves to end of input if not already there.
(ido-magic-backward-char): C-b does like M-b if prev char is /.
Don't switch to buffer mode if repeating C-b at start of input.
(ido-toggle-ignore): C-a only toggles ignore at start or end of
input; else it moves to start of input.
(ido-kill-buffer-at-head, ido-delete-file-at-head): If cursor is
not at end of input, delete rest of input, rather than normal op.