Average the spectra in the stack X and Y positions, with correct weighting for both system temperature and integration time. Generates an error unless both spectra have the same number of quadrants and channels - performs no checking that spectra have same centre frequency, resolution etc..
If the stack contains only one spectrum, in the X-register, then it leaves this spectrum unchanged, but does not generate an error.
Examples:
>> average-spectra <CR>
Averaging quadrant: 1
New effective system temperature: 987.7298
..