[TAP] Do not write optional XML attributes in the /tables when their value is NULL or an empty string.

[ADQL,TAP] Add STC-S and UDFs support in the ADQL parser. Now, it is possible to provide a list of allowed UDFs, regions and coordinate systems. The ServiceConnection of TAP is now able to provide these lists and to propagate them to the ADQLExecutor. UDFs and allowed regions are now listed automatically in the /capabilities resource of TAP. The type 'geometry' is now fully supported in ADQL. That's why the new function 'isGeometry()' has been added to all ADQLOperand extensions. Now the DBChecker is also able to check roughly types of columns and UDFs (unknown when parsing syntactically a query). The syntax of STC-S regions (expressed in the REGION function) are now checked by DBChecker. However, for the moment, geometries are not serialized in STC-S in the output....but it should be possible in some way in the next commit(s).

[TAP] Make valid the /tables document (using a XSD schema correct copy of GAVO for VOSITables ; the IVOA one is incorrect: the attribute targetNamespace is not ...VOSITables...)

[TAP] Fix bug in upload (uploaded tables were given twice to the db checker) & Allow customization of the DB upload schema in the tap factory

[UWS,TAP] Review the exceptions and logs management + Add log file rotation (with a configurable rotation frequency)

[TAP] Fix the /tables output: the UCD node was after UType...it should be just before (warning raised by TAPLint)

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

[TAP] Remove TAPTypes and create a new class to represent a TAP column type: TAPType. + Improve the conversion between VOTable type and TAP type by embedding it in TAPType. + Modify TAPColumn in order to integrate TAPType and that its VotType is just a conversion of a TAPType. {This commit is not compilable.}

[TAP] Rename TAPMetadata.TableIterator into TAPMetadata.TAPTableIterator (it iterates only on the content of a TAPTable object and not on a data table. + Typos