use unicode for HTML export

not utf8-encoded bytes

should close #3807
fix InlineBackend config message

had wrong class name, was unclear.
added new readme in the directory
mention pr folder in whatsnew and CONTRIBUTING
adding a couple of examples

since these are empty files, the eventual tools/ script that will
concatenate these into development.txt can use these as a test case
fix links
apply @takluyver's suggestion
added bolding of "must have"
Fix clashes between debugger tests and coverage.py

coverage.py works by setting the trace function. But so does the
debugger, so we need to re-set it afterwards to get accurate coverage
results.
fix a couple of default block values

should be None

closes #4103

should be backported to 1.1
update parallel magic tests with capture_output API

capture_output now grabs rich data, which changes the results to check
update parallel magics tests with 2.7 APIs
clarify that InlineBackend.figure_format only applies to matplotlib
Declare ip.register_magic_function at class level so that it is included in docs
Update extension docs with new method for defining magic functions.
ZMQ heartbeat: catch EINTR exceptions and continue.

The zmq heartbeat channel exits when it encounters an
"Interrupted system call", thereby causing the qtconsole to
report that it is not responding, despite the console working
perfectly fine. Observed in a large Qt application embedding
the ipython qtconsole.
Fixes #2310
Merge pull request #4115 from takluyver/doc-register-magic-func

Update docs on declaring a magic function
Merge pull request #4102 from takluyver/coverage-debugger-clash

Fix clashes between debugger tests and coverage.py
Merge pull request #4107 from minrk/parallel-magics-fix

update parallel magic tests with capture_output API
Merge pull request #4106 from minrk/clear-block

fix a couple of default block values