Remove sourceTEs option

[tsalo]

Summary

In a discussion that I am unable to locate, I recall someone saying that maPCA would be incompatible with running PCA on z-concatenated data (i.e., using anything other than optimally combined data with the sourceTEs option). Given that we were never able to find a satisfactory rationale or use-case for the argument (see #203), I think that we should remove it.

Next Steps

1. Remove --sourceTEs from tedana CLI, workflow function, and PCA functions.

[eurunuela]

As far as I can tell, maPCA is not compatible with —sourceTEs. I guess it could be implemented in the feature but I personally do not know how atm.

[tsalo]

@eurunuela Thanks! It's good to have that on record from someone more familiar with that code than me. I don't think there's much benefit (if any) to supporting sourceTEs, even if maPCA was compatible with it already, since there's no real conceptual difference between the different options.

[eurunuela]

Totally agree on that @tsalo. I don't see any benefits to supporting sourceTEs either but I'm not very familiar with the rest of the code anyway.