setName() and setDebug() need to be called on a parser element before
the parser element is used as a sub-element in another parser element,
otherwise the debug output is not shown.
Hence the "iterate over all locals" approach works only partially.
Instead add a new decorating function add_element() for the
construction of each parser element, and make sure to enable debugging
inside that function.
Unfortunately there is no clean way to avoid duplicating the parser
element name both in the local variable and in the function argument.
Change-Id: Iaa9ed9b7dbb22ec084070b9c049cf51c841d442c
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
a2e0f19b61