imp module deprecated in 3.4

We still use imp.find_module,(in IPython/utils/module_paths.py)  but
this as no newer drop-in replacement as far as I understand.

Some alternative suggested here:

https://docs.python.org/3/library/importlib.html#importlib.abc.Finder

Deprecated since version 3.3: Use MetaPathFinder or PathEntryFinder
instead.

The various error messages are not clear of the exact version where
this is deprecated.

IPython/core/extensions.py

@@ -13,7 +13,11 b' from IPython.utils.path import ensure_dir_exists'
 from traitlets import Instance
 from IPython.utils.py3compat import PY3
 if PY3:
-    from imp import reload
+    try: 
+        from importlib import reload
+    except ImportError :
+        ## deprecated since 3.4
+        from imp import reload
 
 #-----------------------------------------------------------------------------
 # Main class

IPython/utils/openpy.py

@@ -228,7 +228,11 b' def _list_readline(x):'
 # Code for going between .py files and cached .pyc files ----------------------
 
 try:    # Python 3.2, see PEP 3147
-    from imp import source_from_cache, cache_from_source
+    try: 
+        from importlib.util import source_from_cache, cache_from_source
+    except ImportError :
+        ## deprecated since 3.4
+        from imp import source_from_cache, cache_from_source
 except ImportError:
     # Python <= 3.1: .pyc files go next to .py
     def source_from_cache(path):