Unique_id: move module to Internal_pervasives
doc: do some fixes in the README
doc: add build of the documentation
Efmp: fix references to old name “efmpexp”
Command_line: make persistence path configurable

It is still configurable from the command-line of user-apps but now it
is also configurable from OCaml.
test: Add basic testing of `get_output` and `nohup`
test: create script `run_test.sh`
Efmp: pack module `Unique_id`
Execution_engine: set wrong `Make` jobs completed

Failing to start was leaving the “Make TODOs” as declared, now they are
properly set as “failed”.
test: add testing of `Make` jobs (until it fails)

As the feature is not completely implemented, the most “advanced” tests
currently fail, more tests wil be added as the implementation goes
forward.