(proced-sort-header): New face.

(proced-sort-header): New face.
(proced-sort-header-face): New variable.
(proced-format): Allow format value nil.  Use
proced-sort-header-face for header of sort column.
(proced-format-args): New function.
(proced-grammar-alist, proced-timer-flag, proced-process-alist)
(proced-header-help-echo, proced-field-help-echo, proced-timer)
(proced-toggle-timer-flag, proced, proced-mode): Doc fix.
(proced-refine): Renamed from proced-filter-attribute.  Doc fix.
(proced-sort-header): Bind also to mouse-1.
(proced-move-to-goal-column): Return position of point.
(proced-filter-interactive): Always revert listing.
(proced-format-ttname): Simplify.
(proced-update): Do not keep undo information.  Put point at
beginning of buffer if we generate the first listing.