[CSV-131] Save positions of records to enable random access. First commit for this new feature. Let the ExtendedBufferedReader track how many characters it has read so far.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1625455 13f79535-47bb-0310-9956-ffa450edef68
[CSV-131] Save positions of records to enable random access. 2nd commit for this new feature. Let the Lexer make the underlying reader's character position available through a new package private method.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1625456 13f79535-47bb-0310-9956-ffa450edef68
Add missing @Override.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1625457 13f79535-47bb-0310-9956-ffa450edef68