types. The notion of "unknown type" is different in function of the target
object:
  - a DBType and a FunctionDef have an unknown type if their function
    isUnknown() returns true. In such case, the other functions such as
	isNumeric/String/Geometry() will return false.
  - an ADQLOperand (e.g. ADQLColumn) does NOT have a isUnknown() function.
    But if the type of the operand is unknown, its functions isNumeric(),
	isString() and isGeometry() must ALL return true. Otherwise, just one of
	these functions can return true.

[ADQL] Rename UnresolvedJoin and UnresolvedFunction so that normalizing all UnresolvedXxx exceptions.

[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).

ADQLObject has now a new function: getPosition(). To allow it, the parser and all ADQL query tree item have been modified to define this function properly. The parser is setting this position for all parsed items. The test class/main function "TestGetPositionInAllADQLObject" aims to check that after a parsing all items really have a defined position.

1/ let the function ROUND having 2 parameters
2/ wrap Operations (WrappedOperand) with brackets when there are brackets in the ADQL query

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: Fix an ADQL bug (raised by Dave Morris) in the management of subqueries: before, it was impossible to use (in a clause different from the FROM) columns of a father query inside a subquery.

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).

ADQL: Fix ArrayIndexOutOfBoundsException while initializing a DefaultUDF (User Defined Function) object with several parameters.