serve: Add server sent events for showing pipeline errors in the debug window. The server can now run an endpoint that streams pipeline status, including errors or "fixed" statuses. As a result, I had to investigate using event-loop based server alternatives, before I figured out the correct flag to set in Werkzeug. Support for Gunicorn is therefore now possible, although disabled by default. I will come in handy though when proper support for CMS-mode is enabled.

include README.rst
include CHANGELOG.rst
include LICENSE.rst
recursive-include piecrust *.py mime.types
recursive-include piecrust/resources *
recursive-include tests *.py
#global-exclude .DS_Store
#global-exclude Thumbs.db
#global-exclude Desktop.ini
#global-exclude *.swp
#global-exclude *~
#global-exclude *.bak