Be more explicit in some deprecation warnings

IPython/utils/io.py

@@ -23,7 +23,9 b' from .py3compat import string_types, input, PY3'
 @undoc
 class IOStream:
 
-    def __init__(self,stream, fallback=None):
+    def __init__(self, stream, fallback=None):
+        warn('IOStream is deprecated since IPython 5.0, use sys.{stdin,stdout,stderr} instead',
+             DeprecationWarning, stacklevel=2)
         if not hasattr(stream,'write') or not hasattr(stream,'flush'):
             if fallback is not None:
                 stream = fallback
@@ -44,7 +46,7 b' class IOStream:'
         return tpl.format(mod=cls.__module__, cls=cls.__name__, args=self.stream)
 
     def write(self,data):
-        warn('IOStream is deprecated, use sys.{stdin,stdout,stderr} instead',
+        warn('IOStream is deprecated since IPython 5.0, use sys.{stdin,stdout,stderr} instead',
              DeprecationWarning, stacklevel=2)
         try:
             self._swrite(data)
@@ -60,7 +62,7 b' class IOStream:'
                       file=sys.stderr)
 
     def writelines(self, lines):
-        warn('IOStream is deprecated, use sys.{stdin,stdout,stderr} instead',
+        warn('IOStream is deprecated since IPython 5.0, use sys.{stdin,stdout,stderr} instead',
              DeprecationWarning, stacklevel=2)
         if isinstance(lines, string_types):
             lines = [lines]