(Help-P): Replace `Prev' with `Previous'.

(Help-P): Replace `Prev' with `Previous'.
(Help-M, Help-Xref): Add S-TAB.
(Help-FOO): Update `u' command.
(Help-Xref): Move info about Mouse-2 from `Help-Int'.
Update info about visibility of xref parts.
(Help-Int): Fix `m' command.  Rename `Info-last' to
`Info-history-back'.  Add `Info-history-forward'.
(Advanced): Fix `g*' and `M-n' commands.
(Info Search): Add `index-apropos' in stand-alone browser.
Add isearch commands.
(Emacs Info Variables): Remove `Info-fontify'.
Add `Info-mode-hook'.  Update face names.
Add `Info-fontify-maximum-menu-size',
`Info-fontify-visited-nodes', `Info-isearch-search'.