When using -t SMRY the RSM file is not checked
When using -t RSM the SMRY files is not checked
when running without -t option both RSM and SMRY files are checked together with restart, grid, init and rft file.
This makes the facility usable for the restart read/write code.
Specifically, import the I/O classes into namespace Opm::ecl, and
place the files in physical location opm/io/eclipse, and move the
test utilities to new top-level directory 'test_util/'. While here,
discontinue the 'testutil' static library since most of its features
are now available in the main 'opmcommon' library. This does entail
compiling a few of the test_util/ CPP files multiple times, and
adding the objects to each executable independently.
