We need the dummy version of EZMPI for sequential programs linking
with `Shapelib_03`.

Replace `include_directories` by `target_include_directories` in
`Tests/CMakeLists.txt`. Motivation: some targets do no use ezmpi. This
implies adding directories to `target_include_directories` for
`extraction_eddies`.

In `send_snapshot` and `recv_snapshot`, send and receive a whole
eddy. Read and write a snapshot in `test_send_recv`.