flow: switch it to use the eWoms parameter system

this has several advanges:

- a consistent and complete help message is now printed by passing the
  -h or --help command line parameters. most notably this allows to
  generically implement tab completion of parameters for bash
- the full list of runtime parameters can now be printed before the simulator
  has been run.
- all runtime parameters understood by ebos can be specified
- no hacks to marry the two parameter systems anymore
- command parameters now follow the standard unix convention, i.e.,
  `--param-name=value` instead of `param_name=value`

on the negative side, some parameters have been renamed and the syntax
has changed so calls to `flow` that specify parameters must adapted.

opm/autodiff/BlackoilWellModel_impl.hpp

@@ -2,8 +2,6 @@
 
 
 namespace Opm {
-
-
     template<typename TypeTag>
     BlackoilWellModel<TypeTag>::
     BlackoilWellModel(Simulator& ebosSimulator,
@@ -33,7 +31,6 @@ namespace Opm {
     }
 
 
-
     template<typename TypeTag>
     void
     BlackoilWellModel<TypeTag>::