Add PPG examples

v1.6.7

Add: PPG Examples

Examples for PZ version 1.6.6

Add various examples formats

Examples for PZ version 1.6.1

Add 12-lead ECG example (wfdb format)

Examples for PZ version 1.5.8

v1.5.8

New spo2 example

Examples for PZ version 1.5.7

v1.5.7

Reorder some files