"use strict" in most (if not all) our javascript

+ fix one variable leaking in global nameespace
rename call methods to transform and postprocess

- The `call` methods for nbconvert transformers has been renamed to
  `transform`.
- The `call` methods of nbconvert post-processsors have been renamed to
  `postprocess`.

  pinging @Carreau and @jdrefer, who probably knows who'd be affected by
  this change...  maybe @damianavila, @jakevdp
replace 'transformer' with 'preprocessor'
fixup minor typos from search/replace
renamed transformer to preprocessors
minor typo
capture rich output as well as stdout/err in capture_output

closes #3742
add outputs property on CapturedIO
add --no-display flag to %%capture

document this new magic in whatsnew, and added docs to the resulting object.
updated Basic Output notebook with  new %%capture
default values for RichOutput attributes
tests for utils.capture
subclass RichOutput in ExecuteReply

they are very similar

add another test for good measure.
respect `pylab_import_all` when `--pylab` specified at the command-line

Earlier cleanup cleaned up a bit too much, ignoring this configurable.

should be backported to 1.x
only strip continuation prompts if regular prompts seen first

should be discussed before merge (ping @takluyver),
as it is a significant and sensitive change.

I'm also not sure that it's the right fix, but worth a try.

closes #4059
Merge pull request #3969 from Carreau/usestrict

"use strict" in most (if not all) our javascript

plus fix one variable leaking in global namespace
use unicode for HTML export

not utf8-encoded bytes

should close #3807
fix InlineBackend config message

had wrong class name, was unclear.
Merge pull request #3744 from minrk/capturedisplay

capture rich output as well as stdout/err in capture_output
minor bug fix, define 'var' in dialog.js.

The 'cell' variable isn't defined and causes and error in the
console