add marsbar citation

[Remi-Gau]

We presented an abstract to the Human Brain Mapping conference for 2002; this may be useful as a reference: MarsBaR HBM abstract. It should apparently be cited as:

Matthew Brett, Jean-Luc Anton, Romain Valabregue, Jean-Baptiste Poline. Region of interest analysis using an SPM toolbox [abstract] Presented at the 8th International Conference on Functional Mapping of the Human Brain, June 2-6, 2002, Sendai, Japan. Available on CD-ROM in NeuroImage, Vol 16, No 2.