Release v0.6.6

Adds multithreading configuration ability to prefs.ini (temporal until a GUI is made).
IPv6 support for the Remote IP address.
Improvement for positon solver (improves yaw insensitivity and occasional extreme output values).
Slight reduction on facial landmark jitter.
Improvement efficiency of internal optimization algorithms.
Lowers CPU consumption of face detection step (5x speedup).
Improves face detection step in poor lightning settings.

AIRLegend / aitrack