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.
Removing page.less from base style.less.
Refactoring the center/left justify.
add LazyConfigValue

exposes container methods on container traits, to be lazily evaluated.

Specifically:

- append, extend, insert on lists
- update on dicts
- update, add on sets
AttributeError check on config no longer works

use new `'Class.trait' in config` check
update bundled profiles to use extend
AttributeError no longer raised on missing config
Adding this feature to whatsnew.
add LazyConfig.prepend
adds the optional parameter -s to the magic %load that loads specific function or classes from the python source given. forcing the patch ignoring whitespace changes
skip doctests. comments on the function
fix docstring
better end block detection, ignoring blank lines
add extra blank lines on the test to proof they are ignored
Return value directly from the try block and avoid a variable
assignment.