[wp] smoke tests

src/plugins/wp/Changelog

src/plugins/wp/GuiGoal.ml

src/plugins/wp/GuiList.ml

src/plugins/wp/GuiNavigator.ml

src/plugins/wp/GuiProver.ml

src/plugins/wp/ProofEngine.ml

src/plugins/wp/ProofEngine.mli

src/plugins/wp/ProverErgo.ml

src/plugins/wp/ProverScript.ml

src/plugins/wp/ProverTask.ml

src/plugins/wp/ProverTask.mli

src/plugins/wp/VCS.ml

src/plugins/wp/VCS.mli

src/plugins/wp/doc/manual/wp_plugin.tex

src/plugins/wp/prover.ml

src/plugins/wp/register.ml

src/plugins/wp/tests/wp_plugin/doomed.i

src/plugins/wp/tests/wp_plugin/doomed.report

src/plugins/wp/tests/wp_plugin/doomed_axioms.i

src/plugins/wp/tests/wp_plugin/doomed_loop.i