Compute and return the score for a match with e errors and x location.
@param e Number of errors in match.
@param x Location of match.
@param loc Expected location of match.
@param pattern Pattern being sought.
@return Overall score for match (0.0 = good, 1.0 = bad).
Compute and return the score for a match with e errors and x location. @param e Number of errors in match. @param x Location of match. @param loc Expected location of match. @param pattern Pattern being sought. @return Overall score for match (0.0 = good, 1.0 = bad).