support Hindley-Milner polymorphisms in binds and facts; let_bind(_i): polymorphic version; moved find_free, export_wrt to Isar/proof_context.ML;
support Hindley-Milner polymorphisms in binds and facts;
let_bind(_i): polymorphic version;
moved find_free, export_wrt to Isar/proof_context.ML;

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