Allow filename with extension in find_cmd in Windows.

closes gh-3316 (hopefully)
Add a mode to exec code in %debug magic
Document the new usage of %debug
fix `%magic` output

call lsmagic without underscore

closes #3467
exercise `%magic` in tests
restore "unsaved changes" warning on unload

Autosave is triggered at this event, but it seems to fail sometimes (perhaps when it's too slow?).

closes #3475
update before unload message

mention pending autosave, if applicable
When a notebook is written to file, name the metadata name u''.
Display R errors without Python traceback
Catch some pathological cases inside oinspect

Closes gh-2577
remove yields from test_magic

at request of @fperez
cleanup nt.assert usage in test_magic

use `assert_in` and `assert_equal` in place of a few `assert_true/false`
add parent to Configurable

this adds the notion of a parent and member config,
so the config:

    c.Foo.Bar.attr = value

will only set `Bar.attr = value` for `Bar` instances
which are members of `Foo` instances.
The mechanism for doing this is

```python
f = Foo(config=cfg)
f.b = Bar(parent=f)
```

This Instance config has higher priority than plain class config for Bar,
but still lower priority than direct keyword arg trait assignment.

The main implication this has is to change the standard creation of descendants:

```python
self.bar = Bar(config=self.config)
```

into a direct parent expression

```python
self.bar = Bar(parent=self)
```

This also means that most Configurables will actually have a handle on their parent object.
override null config with parent's config
use `parent=self` throughout IPython

instead of `config=self.config`

only real effective change: IPythonKernelApp.parent has been renamed to IPKernelApp.parent_handle.
don't use parent in launcher tests
Drop patch for compatibility with pyreadline 1.5

Closes gh-1307
allow multi-level Config parentage

now Foo.Bar.Baz can affect a Baz whose parent is Bar whose parent is Foo.

More specificity = higher priority, so Foo.Bar.Baz > Bar.Baz > Baz.
check `parent is not None` rather than `not parent`

Configurables often resolve to zero for some reason
Add test suite for autoreload extension

Closes gh-1912