Implement error overview.

* tex-buf.el (TeX-command): Kill the frame and buffer associated
to the error overview before running commands.
(TeX-TeX-sentinel): Open error overview if
`TeX-error-overview-open-after-TeX-run' is non-nil and there are
errors or warnings to show.
(TeX-LaTeX-sentinel): Ditto.
(TeX-find-display-help): Set `runbuf' to `TeX-active-buffer' since
this function may be called also from the error overview buffer.
(TeX-error-description-faces): Change group to more appropriate
`TeX-output'.
(TeX-error-overview-active-buffer): New variable.
(TeX-error-overview-orig-frame): Ditto.
(TeX-error-overview-orig-window): Ditto.
(TeX-error-overview-frame): Ditto.
(TeX-error-overview-setup): New customizable variable.
(TeX-error-overview-setup): New function.
(TeX-error-overview-goto-source): Ditto.
(TeX-error-overview-make-entries): Ditto.
(TeX-error-overview-next-error): Ditto.
(TeX-error-overview-previous-error): Ditto.
(TeX-error-overview-quit): Ditto.
(TeX-error-overview-mode-map): New variable.
(TeX-error-overview-list-entries): Ditto.
(TeX-error-overview-mode): New major mode.
(TeX-error-overview-buffer-name): New constant.
(TeX-error-overview-frame-parameters): New customizable variable.
(TeX-error-overview-open-after-TeX-run): Ditto.
(TeX-error-overview): New function.

* tex.el (TeX-error-overview): Autoload `TeX-error-overview'.
(TeX-mode-specific-command-menu-entries): Add an entry for the
error overview.

* doc/auctex.texi (Debugging): Document error overview.

* doc/changes.texi: Mention error overview.  Add local variables
to the end of the file.

* doc/todo.texi: Add local variables to the end of the file.
(Wishlist): Update entry about error reporting.
Fix TeX-find-display-help.

* tex-buf.el (TeX-find-display-help): Expand the name of the file to be
visited starting from the directory of the master file.
Prettify file names in error overview.

* tex-buf.el (TeX-error-overview-make-entries): Add optional
`master-dir' argument, to shorten file names when they are relative.
(TeX-error-overview): Pass `TeX-master-directory' as argument to
`TeX-error-overview-make-entries'.
Update Future Development section in manual.

* doc/todo.texi (Mid-term Goals): Remove "More flexible option and
command handling" item: we now have `TeX-command-extra-options'.
(Wishlist): Remove "Poor man's Source Specials": AUCTeX supports
source specials and SyncTeX.
(Wishlist): Remove "multiple completion for \bibliography" item:
"\bibliography" does complete multiple arguments.
Improve selection of the forward/inverse search method.

* tex.el (TeX-expand-list): Set
`TeX-source-correlate-output-page-function' when necessary, in the
"%(outpage)" expander.
(TeX-source-correlate-method): Add an alist as a possible value
and change the default.
(TeX-source-correlate-method-active): Convert to a function.
(TeX-source-correlate-expand-options): Use the
`TeX-source-correlate-method-active' function.
(TeX-source-correlate-mode): Remove setting of the
`TeX-source-correlate-output-page-function' variable and of the
now deleted `TeX-source-correlate-method-active' variable.
(TeX-source-specials-view-expand-options): Use the
`TeX-source-correlate-method-active' function.

* context.el: Update copyright years.
(ConTeXt-expand-options): Use the
`TeX-source-correlate-method-active' function.

* doc/auctex.texi (I/O Correlation): Update documentation of
`TeX-source-correlate-method'.

* doc/changes.texi: Mention change to the default value of
`TeX-source-correlate-method'.
Hide some entries of the Command menu when not available.

* tex.el (TeX-mode-specific-command-menu-entries): Hide "Previous Error"
and "Error Overview" entries when not available.