(fortran-break-before-delimiters): Doc fix.

(fortran-break-before-delimiters): Doc fix.
(fortran-break-delimiters-re, fortran-no-break-re): New defconsts.
(fortran-fill): When filling a string, adjust re-search-backward
argument for special case of string just on fill-column.
When filling non-string, allow one extra char if
fortran-break-before-delimiters is non-nil.  Suggested by
Michael Hagemann <michael.hagemann@unibas.ch>.
Use fortran-break-delimiters-re and fortran-no-break-re to
correctly handle cases such as "**".