Epyc

- Stringified tracebacks so the work better remotely
- Updated build system somewhat

- Added traceback objects to metadata for failed experiments, to help debugging
- Fixed JSON notebooks to handle tracebacks
- Added slightly more documentation in places

- Changed scale of timing metadata from milliseconds to seconds
- Replaced generated doc/conf.py with a static file
- Added creation of HTML doc ZIP file

- Added cancellation of pending results to ClusterLab
- Added Sphinx API documentation
- Converted class and method docstrings to Sphinx
- Made labs treat string parameters as single values, not iterables

- Added Lab.dataframe() method to save going to the notebook
- Added updateResults() at Lab level, removed now-unnecessary
overriding at ClusterLab level
- Optimised updateResults() to grab all completed pending results
in a single network transaction
- Added global wait() to ClusterLab, coding around the
ipyparallel.Client code's wait() method (which can't be used
directly -- see notes in the method)

- Oops, forgot to fix one of the changed method names....