more operations;

structure PolyML is sealed after bootstrap: all ML system access is managed by Isabelle;

ML save_state under control of Isabelle/Scala;

discontinued RAW session: bootstrap directly from isabelle_process RAW_ML_SYSTEM;

--HG--
rename : src/Pure/RAW/multithreading.ML => src/Pure/Concurrent/multithreading.ML
rename : src/Pure/RAW/unsynchronized.ML => src/Pure/Concurrent/unsynchronized.ML
rename : src/Pure/RAW/exn.ML => src/Pure/General/exn.ML
rename : src/Pure/RAW/exn.scala => src/Pure/General/exn.scala
rename : src/Pure/RAW/secure.ML => src/Pure/General/secure.ML
rename : src/Pure/RAW/fixed_int_dummy.ML => src/Pure/ML/fixed_int_dummy.ML
rename : src/Pure/RAW/ml_compiler0.ML => src/Pure/ML/ml_compiler0.ML
rename : src/Pure/RAW/ml_debugger.ML => src/Pure/ML/ml_debugger.ML
rename : src/Pure/RAW/ml_heap.ML => src/Pure/ML/ml_heap.ML
rename : src/Pure/RAW/ml_name_space.ML => src/Pure/ML/ml_name_space.ML
rename : src/Pure/RAW/ml_pretty.ML => src/Pure/ML/ml_pretty.ML
rename : src/Pure/RAW/ml_profiling.ML => src/Pure/ML/ml_profiling.ML
rename : src/Pure/RAW/ml_system.ML => src/Pure/ML/ml_system.ML