Rename the IgnoreEmptyHeaders property to AllowMissingColumnNames

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1612337 13f79535-47bb-0310-9956-ffa450edef68
Prefix everything that is a pure getter with "get" as proposed by Gary Gregory

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1612341 13f79535-47bb-0310-9956-ffa450edef68
Consistently rename Quote/QuotePolicy to QuoteMode

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1612344 13f79535-47bb-0310-9956-ffa450edef68