bridge (constructor): refactoring: - constructors are now in separate modules - constructors are discovered dynamically - factorised generation code from D-Bus in base Constructor. - A generic generation method is now available in base Constructor, using python formatting. - removed bridge/bridge.py in core as it was useless, may come back in the future if needed

Use this module to temporary store files that need to be integrated to other
projects such as Wokkel.

For example, the changeset that introduced this folder adds RSM (XEP-0059)
support to Wokkel. The files in sat.tmp.wokkel are imported over the initial
wokkel files from sat.plugins.__init__.py