fix some masochistic compiler warnings for the GCC 9 pre-release

the flags which I used are
```
-pedantic \
-Wall \
-Wextra \
-Wformat-nonliteral \
-Wcast-align
-Wpointer-arith \
-Wmissing-declarations \
-Wcast-qual \
-Wshadow
-Wwrite-strings \
-Wchar-subscripts \
-Wredundant-decls \
-fstrict-overflow \
-O3 \
-march=native \
-DNDEBUG=1
```

note that some heavy filtering is not the worst idea because DUNE is
far from not emiting any warnings with these flags.

Also, there were some pesky warnings in test_ecl_output which I don't
know how to fix:

```
tests/test_ecl_output.cc:218:73: warning: missing initializer for member ‘Opm::data::Connection::effective_Kh’ [-Wmissing-field-initializers]
```

ebos/eclequilinitializer.hh

@@ -107,7 +107,6 @@ public:
 
         unsigned numElems = vanguard.grid().size(0);
         unsigned numCartesianElems = vanguard.cartesianSize();
-        typedef typename GET_PROP_TYPE(TypeTag, FluidSystem) FluidSystem;
 
         EQUIL::DeckDependent::InitialStateComputer<TypeTag> initialState(materialLawManager,
                                                                          eclState,