Date and Time are converted into a string with the following resp.
formats: 'yyyy-MM-dd' and 'HH:mm:ss'.

[TAP,ADQL] Improve and remake a part of the database connection. Missing javadoc has been added when missing in the modified tables.

[TAP] Improve TableIterator + Adapt ResultSetTableIterator (particularly because of the last commit about TAPType and VotType) + Add a TableIterator for VOTable input: VOTableIterator + Add its JUnit test case

[TAP] Add the interface TableIterator (whose implementations let iterate over any kind of table data set) and its first implementation for ResultSet + JUnit test case