Modifications integrated:

- SSD divided by mean by default
- default radius of 2 for block matching
- min/max altitude offset parameters mandatory and in right order
- use bijection consistency in block matching by default
- discard pixel with low variance by default (100 by default)

ENH: masked disparities in sensor geometry handling with nodata value and mask . NoData value is configurable in output DEM JIRA #OTB-375

BUG: Wrong order of variables for fuzzy membership: param[0] and param[1] refer to var_, whereas param[1] and param[2] refers to var in the reamaining of the code

ENH: StereoFramework map projection is set to wgs by default. bijection filter tolerance have been changed.