Expand unit and integration test coverage

[mrikasper]

• Unit tests: e.g., PCA for aCompCor and differing data sizes
• Completeness of integration tests, e.g., testing different intermediate results substructures to identify processing stages/modules of failure
  • generic test data download Adapt unit/integration test data folder to generic download TAPAS example folder #8
• Integration tests for all visualizations
• Approve PhysIO pull requests by complementing them with suitable unit tests
  • SPM Compatibility: Removing field trip paths PR 181 PHysIO #180 #166: Removing fieldtrip paths instead of spm translationalneuromodeling/tapas#181
  • Remove PCA voxel limitation for aCompCor PR 192 tapas_physio_pca -> no voxel limitation translationalneuromodeling/tapas#192
• Fix license errors in relation to unnecessary use of Matlab Toolbox functions, e.g., nanmean
  • Error due to deprecated nanmean function translationalneuromodeling/tapas#205) and
  • Possible issues with log file translationalneuromodeling/tapas#206
• Integration tests related to Siemens logfile versions filtfilt error translationalneuromodeling/tapas#204
  • New integration tests for Siemens logfile version 3 #10