ipython_directive, report except/warn in block and add :okexcept: :okwarning: options to suppress
PEP8 fix
Guard against self.state is None
Remove explicit passing state arg in favor of self.directive.state
Document previous fix re cython magic support in ipython_directive
add additional clarification in ip_d re prompt stripping
add notebook signing to nbformat
sign notebooks
add nbformat.sign.NotebookNotary
add `ipython notebook trust` subcommand
use configured scheme, not stored scheme when checking signatures

protects against notebook author choosing bad hash scheme.
Notaries sign notebooks now
move `ipython notebook trust` to `ipython trust`

and move App definition to nbformat.sign (maybe it should get its own file).
tweak default profile_dir

needed for testing
test notebook signing
get_output_cell fails with no such output

rather than returning null
Removing Kernel menu.
Add kernel restart button to toolbar.
Cleaning up output management in code and menus.
Removing unneeded select prev/next from Edit menu.