Don't reset the readline completer after each prompt

This makes it impossible to setup a custom completer. The comment says that
"we must ensure that our completer is back in place," but I don't see why. All
that does it make it impossible to use a different completer. One can trick
IPython into not doing this by monkeypatching ip.has_readline to False, but
then certain features like multiline editing are no longer enabled.

See https://github.com/davidhalter/jedi/pull/321.
make default language highlight configurable for html
Deactivate tooltip on tab by default.

Codepath is **not** removed by this.
Update some example notebook with Shift-Tab
Remove tooltip on tab logic
fix test
remove more hard coded layout
split notebook style in 2 files,

app specific/not app specific
recompile css
Use svg by default due to lack of Ghostscript by default on Windows
make close-and-halt work on new tabs in Chrome

this is not possible in Firefox, as new tabs/windows which were *not*
opened via a script ( window.open call ) are not allowed to be closed
via window.close and will yield a message like

--
[11:50:59.691] Scripts may not close windows that were not opened by script. @ http://localhost:8888/static/notebook/js/menubar.js:105
Switch default IPython directory back to ~/.ipython

As discussed at the dev meeting, we care more about a consistent default
across platforms than half-heartedly following the XDG specs.
Update tests for IPython.utils.path
outputarea.js: Wrap inline SVGs inside an iframe

When multiple inline SVGs are included in a single document,
they share the same parse tree. Therefore, style collisions and
use id collisions can occur and upset the rendering.

This patch wraps each SVG inside an individual iframe, ensuring
that SVG's declarations do not collide.

(The SVG representation is kept as XML and not converted to a binary
format, so I do not think this approach precludes the use of d3.js)

Tested on:
* Chrome Version 29.0.1547.57 Debian 7.1 (217859)
* Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130806 Firefox/17.0 Iceweasel/17.0.8

Closes #1866
SVG scoping must be explicitly enabled by the user

SVG scoping is disabled by default, to enable it the user
must call the core.display.SVG constructor with the scoped=True
keyword parameter.
Fix style and typo
SVG: scoped is passed as metadata

Instead of using a svg class to pass scope information
use notebook metadata.

Suggested by Matthias Bussonnier
Support isolated metadata tag for any content

Any content whose metadata contains an `isolated` tag will be isolated
from the rest of the document.

The current implementation wraps isolated content into an iframe.
Notebook isolated content: fix firefox extra-space issue

In Firefox, if the iframe initial height is set to 0, the reported
scrollHeight is too large. Workaround: set the initial height to 1.
Add casperjs test for isolated SVGs