(eword-encoded-word-regexp): Must define when this module is compiled.

(eword-encoded-word-regexp): Must define when this module is compiled.
(eword-decode-structured-field-body): Add new optional argument
`start'.
(eword-decode-and-unfold-structured-field-body): Likewise.
(eword-decode-and-fold-structured-field-body): Likewise.
(eword-analyze-quoted-string): Add new argument `start'; return
(<parsed result> . <end position>) instead of (<parsed result> . <rest
string>).  (std11-analyze-domain-literal): Likewise.
(eword-analyze-domain-literal): Likewise.
(eword-analyze-comment): Changed to alias of `eword-parse-comment'.
(eword-analyze-spaces): Add new argument `start'; return (<parsed
result> . <end position>) instead of (<parsed result> . <rest
string>).  (std11-analyze-domain-literal): Likewise.
(eword-analyze-special): Likewise.
(eword-analyze-encoded-word): Likewise.
(eword-analyze-atom): Likewise.
(eword-lexical-analyze-internal): Add new argument `start'.
(eword-lexical-analyze): Change interface to add new optional argument
`start'.
(eword-extract-address-components): Add new optional argument `start'.