add comment about ignoring the idx
minor changes and added unit-test (log-det)
Merge pull request #1517 from lambday/feature/log_determinant

minor changes and added unit-test (log-det)
added ECG source separation notebook
Merge pull request #1520 from pickle27/develop

added ECG source separation notebook
some minor changes for readiability and style
Merge pull request #1521 from karlnapf/develop

some minor changes