Limit latex equations to page width.
Fixed latex template to support multicol w/ adjustbox.
add page-up and page-down functionality to the autocomplete dropdown
Set axis background to transparent in inlinebackend

Fixes #5727, related to #4608
Updated license to include CC BY 4.0 for documentation, examples, and other materials
Added examples to BSD, and added links to online versions of CC-BY
Moved the list of links of the CC-BY licenses below (I could not get RST to render correctly)
Check for pids when listing nbserver processes
Use check_pid from utils in IPython.parallel
update hmac signature comparison

see https://docs.python.org/2/library/hmac.html#hmac.compare_digest
support Python older than 2.7.7
minor cleanup
warn users running older versions of Python
Update widget serializer/unserializer to allow custom serialization on a trait-by-trait basis.

Serializers/unserializers are given as the trait metadata keys `to_json` and `from_json`.
Give subclasses of the Instance traitlet the option of overriding the klass variable to have a default klass.

This makes it easy to construct traitlets for specific object types and default metadata.  For example, we can have a traitlet for numpy arrays that gives default values for `to_json` and `from_json`:

```python
def np_to_list(a):
    if a is not None:
        return a.tolist()
def np_from_list(a):
    if a is not None:
        return np.array(a)

class NDArray(Instance):
    klass = np.ndarray
    metadata = {'to_json': np_to_list,
                'from_json': np_from_list}
```

Then the NDArray traitlet will by default have the klass and some custom metadata.
Make Container widgets take children as the first positional argument

This makes creating containers less cumbersome: Container([list, of, children]), rather than Container(children=[list, of, children])
Prepend a sentinel value to model ids to distinguish them from normal UUIDs (from Sylvain Corlay).
Change serialization terminology to serialize/deserialize
handle the new status messages in IPython.parallel

avoids creating implicit tasks in the Client’s metadata
and Hub’s task db when status messages arrive.
Update celltoolbar.js

I want to write an extension with multiple select bar. They are supposed to be displayed inline, not in block mode. The better way is to use span instead of div.