The keyword "virtual" signalizes that the function is virtual,
i.e. the function of the derived class is called, even if the
call is on the parent class.
It is not necessary to repeat the "virtual" keyword in derived
classes. To highlight derived virtual functions, the keyword
"override" should be used instead. It results in a hard compile-
error, if no function is overridden, thus avoiding subtle bugs.
Replace "virtual" by "override" where appropriate. Moreover,
replace Q_DECL_OVERRIDE by override, since we require reasonably
recent compilers anyway. Likewise, replace /* reimp */ by
"override" for consistency and compiler support.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
