Merge pull request #202 from hdoreau/master

Removing the (unused and undesired) Communication.strdel function.
Revert "EngineTimer: allow timer with fire delay of 0"

This reverts commit fb5e5de04bf7b5e28f129467cbd856e95a62ba2b.
Added missing docstrings to a handful __init__ methods.
Safe and consistent variable initialization.

This is not _strictly_ required but is safer and looks
more consistent.
Fixed wrong variable assignment.

client instances have no _current_client attribute.
The fixed statements silently failed but the actual
variables were indeed not properly assigned.