(apropos-show-scores, apropos-orig-regexp)

(apropos-show-scores, apropos-orig-regexp)
(apropos-all-regexp, apropos-synonyms, apropos-words)
(apropos-all-words): New variables.
(aprpos-words-to-regexp, apropos-rewrite-regexp)
(apropos-calc-scores, apropos-score-str, apropos-score-doc)
(apropos-score-symbol): New functions.
(apropos-command, apropos, apropos-value, apropos-documentation):
Allow keywords in addition to regexp. Added scoring.
(apropos-documentation-check-doc-file)
(apropos-documentation-check-elc-file): Added scoring.
(apropos-print): Sort according to score.