empty signal class
register_signal, test with rtpsession
progress on signals
merging develop
progress on signals
Merge branch 'develop' into signals

Conflicts:
	switcher/quiddity.h
Merge branch 'develop' into signals

Conflicts:
	switcher/quiddity.h
Merge branch 'develop' of code.sat.qc.ca:switcher into signals
fix quiddity.h
Merge branch 'signals' of github.com:nicobou/switcher into signals + signal doc

Conflicts:
	switcher/quiddity.h
add return type to json signal description
add hook to signal
filter and serialize in signal hook
refactor _subscriber into _property_subscriber
subscribe to signal from quiddity class
quiddity signal subscriber class
refactor list_subscriber into list_property_subscriber
add dignal subscriber class
Merge branch 'signals' of github.com:nicobou/switcher into signals
quiddity life manager uses signal subscribers