`NEW_PROP_TAG` is now a definition and not just a declaration.
Eliminate superfluous declarations, include headers with definitions.
Make one necessary forward declaration explicit.
- when an episode/report step is over, the next is started by endEpisode()
- the problem does not deal with updating the simulation time anymore
- rename `episodeIdx` in to `reportStepIdx` the 'EclWriter' because
this variable is -- and always has been -- the report step number
used by some parts of `opm-output`'s ECL writing code (the report
step number is equivalent to the episode index plus 1). IMO, the
output and parser code should be made more consistent in regard of
whether it expects 0-based or 1-based indices, but this is a story
for another day.
the speedup gained by parallelism here are simply not worth the
headaches.
note that `flow` is unaffected by this because it uses
`Opm::BlackoilWellModel`.
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]
```
IMO the term "vanguard" expresses better what these classes are
supposed to do: level the ground for the cavalry. Normally this simply
means to create and distribute a grid object, but it can become quite
a bit more complicated, as exemplified by the vanguard classes of
ebos..
