Update construct_stim_matrices.py

[JonathanShor]

Guard against v[: len(v) - temp] wrapping. This could happen in the case that len(v) < prenumlag + postnumlag. Fix as mentioned in #183

[kendrickkay]

Jonathan - thank you for taking a look at this and proposing a fix. We have a matlab-to-python port of GLMsingle that we are trying to maintain. The intention is that the Python version is an exact port of the Matlab (well, at least to identical behavior). If you are willing to clean up and/or fix the Python port of constructstimulusmatrix.m, that would be great

[kendrickkay]

The matlab version is in https://github.com/cvnlab/knkutils/blob/master/mri/constructstimulusmatrices.m (it's a function declared at the bottom of the file). I will proceed under the assumption that the matlab version is correct, and so the job of the python port is to achieve identical behavior

[kendrickkay]

There aren't any other ramifications of the code that we are talking about here, so if you want to clean it up, that shouldn't be a problem

[JonathanShor]

Sure, happy to put some maintenance work into the file in general. My matlab is a bit rusty, but I'll take a look at the referred function and ensure they're functionally equivalent as best I can.

I'll be busy the next few days, but should have this done next week.

[kendrickkay]

Hi Jonathan, I assume this fell by the way side. Did you want to do some checks? And/or do you think the merge request here is ready?