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

syntax: glob
*.pyc
*.pyv
*.swp
*.swo
tags
twistd.log
twistd.pid
bridge_constructor/generated
_trial_temp/
sat.egg-info
*.un~
dist
MANIFEST
build
ctags_links/
Session.vim