Use the more powerful signatures module to display function argument signatures. In particular this works better for functions wrapped with functools.wraps (at least on Python >= 3.4)
Use native map when possible

Implemented on all modern browser.

There is a small behavior difference between $.map and Array.prototype.map
but we don't rely on it.

(jQuery flatten arrays and filters null-like)
use `pip install .[all]` on travis

can't actually use `.[all]` syntax, instead using `file://$PWD`,
but the principal is the same.

get wheels from minrk/travis-wheels to expedite installation
remove timings in travis.yml

Travis does its own timing now
add 'requests' as test dependency

since it is one
create new terminals with POST /api/terminals

instead of GET terminals/new

to be consistent with creating new notebooks.

We had to stop using GET notebooks/new
because browsers would create new notebooks when making preview thumbnails for commonly visited pages, etc.
I assume the same issue would apply to terminals
upate exmaple notebooks to nbformat v4
deprecate heading cells in UI

- removed from Kernel Menu
- Main toolbar warns via shouty dialog
- keyboard shortcuts still work to make headings in markdown cells, with no warning
Make a window immediately, and set its location on response

Avoids the need for async:false
Merge pull request #6846 from minrk/deprecate-heading-ui

deprecate heading cells in UI
Close new window on error creating terminal
Fix bug where cell toolbars are not redrawn,
when cell metadata is changed.
distinguish capture_output from buffer_output

allow capturing output without silencing it,
which is useful for slimerjs,
which requires looking at output to determine failure.
DEV: Support for configurable list of extra jinja template directories.
Merge pull request #6860 from minrk/slimerjs

distinguish capture_output from buffer_output
DEV: Add IPython.html to the default template path.

This makes it possible to override a file with a template that also
inherits from that file.

For example, this makes it possible to override a single block of
notebook.html by creating a file called notebook.html that inherits from
templates/notebook.html.
Update components to codemirror 4.7
Merge pull request #6865 from takluyver/cm4.7

Update components to codemirror 4.7
allow multiple forms of latex math in test_markdown

different versions of pandoc use different escapes
Merge pull request #6863 from minrk/markdown-tex-math

allow multiple forms of latex math in test_markdown