don't use singleton pattern for child_list * child-list.h, child-list.cc: Don't use singleton pattern. * interpreter.h, interpreter.cc (interpreter::m_child_list): New data member. (interpreter::get_child_list): New method. * interpreter-private.h, interpreter-private.cc (__get_child_list__): New function. * pager.cc, sighandlers.cc, toplev.cc: Access child_list through interpreter.

--- a/libinterp/corefcn/interpreter.cc	Sun Feb 11 09:20:36 2018 -0500
+++ b/libinterp/corefcn/interpreter.cc	Sun Feb 11 11:17:34 2018 -0500
@@ -354,6 +354,7 @@
       m_symbol_table (),
       m_evaluator (*this),
       m_stream_list (*this),
+      m_child_list (),
       m_url_handle_manager (),
       m_cdef_manager (*this),
       m_gtk_manager (),