(word-help-switch-help-file): Added support for completion.
(word-help-complete, word-help-complete-list)
(word-help-complete-index, word-help-extract-matches)
(word-help-make-complete): New functions/variables for completion.
(word-help-mode-alist): Enhanced search regexps.
(word-help-index-mapper): Defaults now to extracting the first word.
(word-help-mode-alist, word-help-index-mapper)
(word-help-main-index, word-help-main-obarray)
(reset-word-help, set-help-file, word-help-process-indexes)
(word-help-goto-index-node): Doc fixes.
(word-help-goto-index-node): Requires passing the keyword.
Uses this in the a new and enhanced magic indexing routine.
(set-help-file, word-help): Handle `completion-ignore-case' better.
(word-help-extract-index): `case-fold-search' better handled.
(word-help): Magic guessing of relevant help file put in new
function word-help-find-help-file.
(word-help-guess-all): New subroutine.
(word-help-guess): Use word-help-guess-all.
May optionally copy only upto the cursor,
instead of the entire keyword.
