Adding three new 2D functions, the easy ones that use a Gaussian distribution of parameters.
Changed the parsing of constraints to only build a constraint wave for those parameters that are not being held. failing to do so results in an "unknown error" from curve fitting. This fix was done in both the 1D and 2D wrappers.
Changed the default mask that was two pixels all around to now mask out the beamstop for 2D data sets. 8 pixel radius is currently hard-wired in PlotUtils2D - and is generated as the fit is dispatched, automatically determining the beam center from the data set.
