remove codename
DOC : fixed minor error in using topological sort

`topological_sort` is a function in `nx` not an instance method
of a directed graph.
make spin_thread tests more forgiving of slow VMs

test metadata directly and increase timeouts
Fix starting notebook server with file/directory at command line.

The base class implementation of parse_command_line uses update_config,
which ensures that the change event fires for the config traitlet. This
copies that.

Closes gh-5460
Merge pull request #5464 from takluyver/i5460

Fix starting notebook server with file/directory at command line.
Merge pull request #5463 from minrk/spin-slow

make spin_thread tests more forgiving of slow VMs
Merge pull request #5462 from tacaswell/dag_docfix

DOC : fixed minor error in using topological sort
update link

The page is in the sphinx docs, not on the main website.
Merge pull request #5450 from minrk/no-codename

proposal: remove codename
print_figure returns unicode for svg
Merge pull request #5452 from minrk/svg-decode

print_figure returns unicode for svg
Add support for PyQt5.