Revert example MOD files in user guide to mode_compute=4
The estimation examples in the user guide are not behaving nice with mode_compute=4, because of the non-deterministic nature of estimation. Many users were confused because on some runs, the example were failing because the hessian at the mode was not definite positive.
The problem is that the examples are now a lot slower than before.
We should revert back to mode_compute=4 when #85 (closed) is fixed and we have a way to fix the seed.