[ADQL] Fix SQL translation of NOT BETWEEN (before it was translated by just BETWEEN ; NOT was forgotten)

[ADQL] Fix SQL translation of operations' alias: now, the alias is always surrounded by double quotes (so a sum between two numbers won't have the default alias +, but it will have +)

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

ADQL: Fix big bug: no parenthesis in the SQL translation for ADQL constraints with parenthesis ( ex: A AND (B OR C)) )

ADQL: Correct version number for all modified ADQL related classes since the official v1.1 release. Now, version number after any modification in ADQL is v1.2.

ADQL: Completely change/improve Joins management, and particularly NATURAL JOIN and USING JOIN. Now, every joined columns are represented by a DBCommonColumn instance which has a given table coverage.
Before, there was a problem while using at least 3 or 4 NATURAL JOINs. Bug raised by Menelaos Perdikeas (ESAC).