New feature - Evaluation metric

[camposdp]

Knowing the required time to activate the FES (EEG classification identifying the motor imagery pattern) is an important metric to evaluate the system.

The FW should have a method to record this time.

The main goal is to measure biosignals from other sensors (such as ECG) to measure physiological aspects that may affect the classifier's accuracy. This way, along with the time between the "stimulus" and "activation", some selected channels should be recorded.