The TFCE behaviour do not match exactly the one in the SPM version of swe

This is linked to MR !5 (merged). In brief,

• The TFCE delta parameter is always set to 0.1 in the SPM version (the user cannot alter this) while it is max(TFCE-score)/100.0 per default in the fsl version or it can be set by the user using the option --tfce_D <H>
• In fsl, the TFCE connectivity parameter is set to 6 per default using the option -T or 26 using the option --T2. In SPM, it is set to 18 per default (I had to temporarily override this to set it to 6 for the benchmark). In FSL, the user can override it but not in SPM.
• (The TFCE score in fsl) * (the TFCE delta) = (the TFCE score in SPM). This is not an issue per se because it is only a common multiplier scalar value across voxels and this does not affect the WB p-values. Nevertheless, I believe the SPM version makes more sense (because, to my optinion, the TFCE score should not scale with the value of TFCE delta) and maybe we would like to harmonize this or not.

I do not believe that these are critical points and we can discuss this a bit later with @nichols in case we would like to change something or not.