Use default OS shell to run system commands

Instead of using os.system which uses /bin/sh, this uses subprocess.call (the replacement of os.system) to run the command using the default shell of the OS. With this, one can use more advanced commands for bash, zsh, ksh, ...

I do not have a win32 system to test this modification, so maybe line 2236 can also be changed like 2239.
Added new option in %%cython cell magic to specify the module's name.
Add --name option in %%cython cell magic to specify the Cython module's name.
Use default OS shell to run system commands

Instead of using os.system which uses /bin/sh, this uses subprocess.call (the replacement of os.system) to run the command using the default shell of the OS. With this, one can use more advanced commands for bash, zsh, ksh, ...

I also edited the docstring, added comments and fixed the handling of return codes.
Added top level convert class, updated init.py to load v#s
Notebook version conversions done right?
Fixes (iptest), simplified v1, v2, .. , vX import code
Relative import (suggested by @MinRK)
Revert b23f5b1525e76d5a
Update connect.py

Fixing a bug on windows 7 32 bit : 

[IPythonQtConsoleApp] ERROR | Could not setup tunnels
Traceback (most recent call last):
  File "C:\Anaconda\lib\site-packages\IPython\consoleapp.py", line 304, in init_
ssh
    newports = tunnel_to_kernel(info, self.sshserver, self.sshkey)
  File "C:\Anaconda\lib\site-packages\IPython\kernel\connect.py", line 364, in t
unnel_to_kernel
    password = getpass("SSH Password for %s: "%sshserver)
  File "C:\Anaconda\lib\getpass.py", line 95, in win_getpass
    msvcrt.putch(c)
TypeError: must be char, not unicode
[IPythonQtConsoleApp] Exiting application: ipython-qtconsole
When calling getpass,
TypeError: must be char, not unicode
Switch correctly to the user's default matplotlib backend after inline.

If '%matplotlib inline' was called first, we'd incorrectly revert to
inline when plain '%matplotlib' was called, instead of loading the
user's default GUI.  If the user called '%matplotlib' first (without
'inline') it worked correctly, but not in the other order.

The fix is to read the backend from the original defaults, not from
the runtime data structure.
Add comment as per PR discussion, indicating MPL 1.1 is now required.
Add information to what's new about new MPL 1.1 requirement.
Fixing less @import paths in auth/base/tree.

These paths were problematic for --NotebookApp.use_less=True mode.
Indenting MathJax rendered equations in rendered_html divs.

This is designed to match the indentation level of MathJax equations
in output.
Compiling CSS for this branch.
Centering for tables/images/math in Markdown.
Adding 1em spacing above and below tables in rendered html.
Removing extra comment.
The 'name' argument to the %%cython cell magic is no longer a list.
Added test_cython_name.