sampsapursiainen/zeffiro_interface: May2021

10 May, Classical Sparse Method plugin added, containing dSPM, sLORETA, and Sparse Bayesian Learning. (That is apparently moved to main) 10 May, MUSIC plugin added. (That is apparently moved to main) 10 May, Beamformer plugin added. (That is apparently moved to main) 17 May, Gaussian mixature model clustering app added. 17 May, Some warning messages added to FindSyntheticSource. 24 May, Beta versions of Exponential prior (EXP) inversion app's added. 26 May, Gaussian mixature model clustering app threshold bug fixed