Make `AbstractRowsEventDataDeserializer` methods protected

[rhauch]

Most of the AbstractRowsEventDataDeserializer methods are private, which makes them impossible to override without overriding the deserializeRow(...) method and duplicating all of the logic in the class. Please make the methods protected and change the return type of most of the methods called in deserializeCell(...) to Serializable.

My project that is using the MySQL Binlog Connector library is using Java 8, and I'd like my project to override many of the date- and time-related methods. For example, the rather than the deserializeDate method return a java.sql.Date and use Calendar to assume the current time zone and convert the MySQL value into a java.sql.Date, I would much rather create a java.time.LocalDate object that is semantically identical to the MySQL value, and then deal with that LocalDate object later on in my code. This currently is not possible since the methods are private, but would be possible if the deserializeDate method were changed to protected and its signature is defined to return a Serializable rather than java.util.Date.

I plan to submit a pull request with the proposed changes. If I do this very soon, would you consider releasing a patch to 0.3.1?

[rhauch]

BTW, many of the private methods are also static, and these can't be overridden as easily. Do they need to be static, or can they be changed to not be static?

[shyiko]

0.3.3