refactor symbol_record object When referencing non-local variables, look in correct parent scope context. Cache pointer to parent scope for non-local access. Don't cache pointer to declaration scope. * symrec.h, symrec.cc (symbol_record::symbol_record_rep::m_fwd_scope): New data member. (symbol_record::symbol_record_rep::symbol_record_rep): Eliminate symbol_scope argument. Change all uses. (symbol_record::symbol_record_rep::assign, symbol_record::symbol_record_rep::do_non_const_unary_op): New argument, context Change all uses. Don't look to forward reference here. (symbol_record::symbol_record_rep::varref, symbol_record::symbol_record_rep::varval): New argument, context. Change all uses. Use context from forward scope when forwarding to non-local reference. (symbol_record::symbol_record_rep::clear, symbol_record::symbol_record_rep::is_defind, symbol_record::symbol_record_rep::is_variable, symbol_record::symbol_record_rep::dump): New argument, context. Change all uses. (symbol_record::symbol_record_rep::bind_fwd_rep): New argument, fwd_scope. Change all uses. (symbol_record::symbol_record_rep::bind_fwd_rep, symbol_record::symbol_record_rep::unbind_fwd_rep): Return after forwarding. (symbol_record::symbol_record_rep::get_fwd_scope_context): New function. (symbol_record::symbol_record_rep::get_decl_scope_context): Delete. (symbol_record::symbol_record_rep::m_decl_scope): Delete data member and all uses. (symbol_record::symbol_record): Eliminate symbol_scope argument. Change all uses. (symbol_record::find, symbol_record::assign, symbol_record::do_non_const_unary_opt, symbol_record::varval, symbol_record::clear, symbol_record::is_defined, symbol_record::is_undefined, symbol_record::is_valid, symbol_record::is_variable, symbol_record::dump): New arg, context. Change all uses. (symbol_record::decl_scope): Delete. (symbol_record::bind_fwd_rep): New arg, fwd_scope. Change all uses. * load-save.h, load-save.cc (do_save): New argument, context. Change all uses. (save_vars): Work with scope instead of symbol table. * variables.cc (symbol_info::symbol_info, symbol_info::append): New arg, context. Change all uses. * oct-lvalue.h, oct-lvalue.cc (octave_lvalue::m_context): New data member. (octave_lvalue::octave_lvalue): New argument, context. Change all uses. * pt-decl.h (tree_decl_elt::is_defined, tree_decl_elt::is_variable): New argument, context. Change all uses. * pt-id.h, pt-id.cc (tree_identifier::link_to_global): New argument, global_scope. (tree_identifier::is_defined, tree_identifier::is_variable, tree_black_hole::is_variable): New argument, context. Change all uses. * pt-misc.h, pt-misc.cc (tree_parameter_list::is_defined): New argument, context. Change all uses.