make examples now builds all c++ examples but some of them are in fact
empty skeletons. Those either need some c++ love or the final eo api to
be ready (eg. menu, popup, ...).
I removed some examples that don't have an exact equivalent in EO since
the widget is legacy only.
This fixes all warnings for "make examples" for:
-Wunused-parameter
-Wshadow
-Wformat-security
-Wenum-conversion
Some remaining warnings include:
-Wdeprecated-delcarations