add_prover: plain prover function, without thread; removed obsolete atp_thread interface; moved kill_excessive into main thread manager loop -- avoids race condition wrt. register/unregister; start_prover: register/unregister self -- avoids race condition;
add_prover: plain prover function, without thread;
removed obsolete atp_thread interface;
moved kill_excessive into main thread manager loop -- avoids race condition wrt. register/unregister;
start_prover: register/unregister self -- avoids race condition;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle