Some progress on EMF bqckend. Refactoring machines code

src/backends/EMF/EMF_backend.ml

src/backends/EMF/EMF_common.ml

src/compiler_stages.ml

src/corelang.ml

src/corelang.mli

src/lustre_types.ml

src/machine_code.ml

src/machine_code_common.ml

src/machine_code_common.mli

src/machine_code_types.ml

src/normalization.ml

src/typing.ml