Class version and user defined properties xml2TClass

The percolation of all kind of properties and class version to
TClass is now in place.
The version is a special case. It has to be included in the selection
rule in the XML reader. Indeed the class selection rules are used to
set the version of particular TClass instances.
The genral properties are percolated via the AST modifying in the
dictionary the TAttributeMap of the TClass associated to a particular
class.
Fix small typo (double decl)

Removed double declaration introduced by mistake in
6388fefc5ff681a0289166c8804ddc3a59d51075