Refresh PropertyTreeWidget only when it's visible.
Add SerialPort and PacketReader utilities. Also add Logger class.
Make argument required.
Fix time passed to a Smoother - it should reflect time since last value change.
Add systems/slip-skid module.

Computes slip-skid indicator based on acceleration vectors taken from IMU.
Add SI::Temperature.
Refactor I2C API and add I2C::Device.
Actually add SI::Temperature files.
Add double / Time => Frequency operator.
New config for Flightgear.
Disable 'line edit' when property contains binary data.
Add configuration widgets.
Add missing Makefile.
Log exceptions other than ParseError in io/link.