Signal strength threshold not being properly enforced

[LBlend]

The way the signal strength threshold is enforced may be problematic and cause the application to count the wrong number of devices.

This will happen all of the following happens:

1. A device enters the vicinity of the threshold and triggers a DeviceAdded event
2. The device goes outside the threshold but stays within the vicinity of the host device, not causing a DeviceRemoved event.

This is a critical bug because it may cause the application to gather bad data during training.

The bluer library which is used doesn't seem to provide any way to continuously check the signal strength of connected devices. Therefore it is likely that this library will need to be replaced. I don't know any other way of fixing it.