the automatic datatype detection was missing for CENTROID functions.
--
Additionally, some JUnit test files of the `adql` package has been moved to
the correct location.

This is easily possible for concatenations, string constants and User Defined
Functions having a FunctionDef. A new special datatype was needed for
numeric functions and operations: UNKNOWN_NUMERIC. This special type
can not be set with FunctionDef.parse(...) and it behaves exactly like the type
UNKNOWN, except that DBType.isNumeric() returns true (as .isUnknown()).
Thus, while writing the metadata of a result in TAP, nothing changes:
an UNKNOWN_NUMERIC type will be processed similarly as an UNKNOWN type:
to use the type returned from the database ResultSet or to set VARCHAR.
(no modification of TAP was needed for that)

[ALL] Update ANT build scripts to test all existings JUnit tests before compiling. In case of error, the compilation does not complete.