Update IPython Pygments lexers.
Remove executable flag on __init__.py
Update code for making sphinx aware of IPython console lexer.
Add some discussion about new lexers.
Make IPyLexer available in Pygments as 'ipython' and 'ipython3'.
Skip doctests for IPythonConsoleLexer since they aren't doctests.
Update docstring for IPythonConsoleLexer.
Insert copyright again.
Updating some comments to reflect the actual code.
lexerself -> lexer.
More updates to comments and docstrings.
tweak formatter.for_type

- for_type(cls) nondestructively queries the current formatter (previously disallowed)
- for_type(cls, None) clears the current formatter (previously queried current)
exercise formatter.for_type in tests
Make 'matplotlib' optional when using the ipython directive.
Add `ipython_execlines` option to IPython directive.
Update module docstring for IPython directive.
Fix bug where exec_lines was ignored within ipython directive.
Add 'float' option to @doctest pseudo-decorator.
add lookup logic based on apptools.type_registry

adds

- formatter.lookup(instance)
- formatter.lookup_by_type(type_or_type_string)
- formatter.pop(type_or_type_string)

changes:

- support 'module.name' in formatter.for_type
more formatter type lookup tests