Incorporate SOFA convention GeneralFIRE

[VeraE]

(Monaural) room impulse responses (RIRs) of the loudspeaker array in Rostock are stored as SOFA files with the convention GeneralFIRE. We could include this convention in get_ir() so that it's possible to simulate a loudspeaker array in a room by loading RIRs from a SOFA file. What do you think of this?
The drawback I see is that I don't know which other types of data GeneralFIRE is used for that don't make sense when using them in this way in the SFS toolbox. This convention was created newly when I released my data. I don't know if it has been used by someone else since then.

[fietew]

I think its worth implementing it. The major modification would be, that the current functions have to support single-channel (or other-than-dual-channel) data.

@hagenw : We may also think about renaming the SFS_binaural_synthesis directory or merging it to SFS_ir, because the GeneralFIRE does not reflect anything binaural, anymore.