Hiding useless Qt Meta methods in Implementation Helper

[David Nolden]

I cannot remember having seen those functions, I think they're already
filtered out. That is done simply by filtering out all functions with
"range().isEmpty()", which catches all functions that were expanded
from macros, and thus have an empty range in the source document.

The only problem I'm aware of is the functions created due to
Q_PRIVATE_SLOT. Maybe we can solve those by making those functions
inline-implemented, eg. by adding a "{}" behind the function
signature.