[Inout] Changes and documents external API.

src/plugins/impact/pdg_aux.ml

src/plugins/inout/Inout.ml

src/plugins/inout/Inout.mli

src/plugins/inout/outputs.mli

src/plugins/reduc/collect.ml

src/plugins/scope/datascope.ml

src/plugins/slicing/fct_slice.ml

src/plugins/slicing/slicingCmds.ml

src/plugins/slicing/slicingState.ml

src/plugins/sparecode/globs.ml

src/plugins/sparecode/register.ml

src/plugins/sparecode/spare_marks.ml

src/plugins/studia/reads.ml

src/plugins/studia/writes.ml

tests/slicing/simple_intra_slice.ml