Open download in a new window instead of changing the URL

Closes gh-6764
Fix an issue in the `kernel_running` function of the JS tests,
This fix allows the JS test to be ran against a remote server
with a higher than LAN latency.  This bug in our testing
framework was exposed when running `iptest js/widgets --url`
against tmpnb.
Merge pull request #6766 from takluyver/i6764

Open ipynb download in a new window instead of changing the URL
Merge pull request #6768 from jdfreder/remotetestfix

Fix an issue in the `kernel_running` function of the JS tests,
Qt: only trigger call tips automatically on open parenthesis

call tips were being requested on every change to the document, causing performance problems
don't pick up tokens right of cursor

inspection of `foo(|a` was picking up 'a'
instead of 'foo' due to an off by one error
Handle some tricky Comm lifecycle issues

* If the comm was a primary comm, but there was an error opening it, _closed was False, which is wrong
* If Comm.close() was called, but an error happened, it still appeared to be open

This change makes the _closed attribute more conservative.  If _closed is False, the comm is definitely open for messages.  If _closed is True, we either didn't initialize correctly, or we tried to close at some point.
Unregister comm if there is an error in publishing the comm open message
only sort small dicts and sets in lib.pretty

The sorting caused performance problems when displaying large collections,
even when the result would be truncated.
add info-level log indicating that notebook is being executed
add `nbconvert --execute` flag

for enabling the ExecutePreprocessor
Merge pull request #6780 from minrk/nbc--execute

add `nbconvert --execute` flag
Merge pull request #6769 from minrk/qt-inspect-request

Qt: only trigger call tips automatically on open parenthesis
Merge pull request #6775 from jasongrout/comm-lifecycle

Handle some tricky Comm lifecycle issues
Fixed "data" to "text" change in message spec

This fix was accidentally omitted when the message spec recently changed.
Merge pull request #6788 from dsblank/patch-2

Fixed "data" to "text" change in message spec
Support specifying requirejs modules for widget models
Support specifying requirejs modules for comm targets
Correct the example notebook link to What is the IPython Notebook?
Fix bad JSON link and inconsistent link formatting.