Jace unicorn hybrid black devicepreset

[Cyno00]

changes:

(both script and device interface) no longer raise exceptions when find_unicorn()

(both script and device interface) find_unicorn() now repeatedly (blocking) scans for devices using bluetooth.discover_devices() until one and only one is found. then returns that device ready to go

device interface now only uses find_unicorn() and brainflow to discover and set up unicorn device in start_stream, instead of init

[HaowenWeiJohn]

The add button click function should not contain any While Ture loop.

Should pop a message with popup window that tells why it fails to start the sensor.

[HaowenWeiJohn]

Unicorn Integration in MainWindow and ScriptingInterface done!