add menu to switch between hsplit and vsplit pager

Right now, either hsplit or vsplit must have been used when the widget
was started up.
move paging style switching into console_widget
mods to install mathjax from an explicitly downloaded tar or zip file
Add framework for AST transformations of input code.
Add test that a failing ast_transformer is unregistered.
Fix warning message for unregistering AST transformers.
Fix IPython.utils.warn API so messages are automatically displayed followed by a newline.
Added bracket matching for code cells
Working versions of formatters for files and directories that are generated within an IPython notebook session. This is useful for integrating tools like QIIME with the IPython notebook as it allows users to generate QIIME's HTML visualizations and open them in new pages in their the web browser.
fixed typo what caused text to be displayed rather than link
documentation modification
removing extra import statement
Refactor notebook to use Jinja2 instead of tornado templates
Update print notebook template to Jinja2
fix paths for jinja2 so they work in installed ipython instances
Move notebook.html back to original location
renamed classes as recommended by @takluyver
added test file for the display module, beginning with basic tests of the FileLink, FileLinks, and DirectoryLink classes
added tests of formatting functionality
updated the documentation to describe the FileLink and FileLinks objects. skipping DirectoryLink right now as I don't think this will be widely used