tesa_sspsir and pop_tesa_sspsir functions requires a special Matlab toolbox

[tuomasmutanen]

The use of input parameters 'manual', 'timeRange' ends up calling a Matlab function dsigmf, which is part of an optional Fuzzy logic toolbox. Not all subscriptions have this toolbox. Because the dsigmf does nothing fancy, I suggest we replace it with a custom nested function. I can do a pull request to solve this issue.