[ENH] add support for perf, meeg, pet templates

[Remi-Gau]

relates to #55 and #14

[Remi-Gau]

for ASL it will give this

@tsalo this clearly not perfect but this will give a base to start from.

In session None, 
[cyan]MRI data were acquired on a 3 Tesla MRI scanner using a DISCOVERY_MR750 system from GE.
The software version was 24_LX_MR_Software_release:DV24.0_R02_1607.b.[/cyan]
[cyan]One run of   gradient recalled (GR) steady state, spoiled, and segmented k-space single-echo structural MRI data were collected (repetition time, TR= 7.332 ms; flip angle, FA= 9°; echo time, TE= 3.02 ms; field of view FOV= ?x? mm; matrix size= ?x?; voxel size= ?x?x? mm; UNKNOWN slices).
[/cyan]
[cyan]spiral spiral research mode (RM) no sequence variant perfusion MRI data were collected (UNKNOWN slices; repetition time, TR= UNKNOWN ms; flip angle, FA= 111°;; echo time, TE= 10.53 ms; field of view FOV= ?x? mm; matrix size= ?x?; voxel size= ?x?x? mm;
[/cyan]

Dicoms were converted to NIfTI-1 format.