Handle different start and end times of components

• connect and _connect get an argument start_time that is to be passed to try_connect instead of self.time
• Connect helper pushes data twice: once for start_time and once for info.time (if it is not equal to start_time)
• Starting time can be passed to component's run(), and is auto-determined if not provided

Basically, only the changes in interfaces.py, schedule.py, component.py and connect_helper.py are of interest. The rest is fixes for the breaking change to the interface.

Fixes #4 (closed)