plugin invitation: pubsub invitations: - new Pubsub invitation plugin, to have a generic way to manage invitation on Pubsub based features - `invitePreflight` and `onInvitationPreflight` method can be implemented to customise invitation for a namespace - refactored events invitations to use the new plugin - a Pubsub invitation can now be for a whole node instead of a specific item - if invitation is for a node, a namespace can be specified to indicate what this node is about. It is then added in `extra` data - an element (domish.Element) can be added in `extra` data, it will then be added in the invitation - some code modernisation

# Minimal makefile for Sphinx documentation
#

# You can set these variables from the command line.
SPHINXOPTS    =
SPHINXBUILD   = sphinx-build
SOURCEDIR     = .
BUILDDIR      = .build

# Put it first so that "make" without argument is like "make help".
help:
	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

.PHONY: help Makefile

# Catch-all target: route all unknown targets to Sphinx using the new
# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
%: Makefile
	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)