in grid.norm() metric can be a scalar
periodicGrid centered by default
added metric to plot* in Trajectory + infty metric
added null() and cut() to Trajectory
correction to degrad
moved kdv-independant stuff to ps1d + earthRep mod
	modified:   earthRep.py
Minor modif to kdvParam and earthRep.py
perdiodicGrid in dergres and moved earthRep

.... moved to kdvOSSE
deleted earthRep
minor modif
minor modif: default values
modif waterfall() for SpectralTrajectories
.... waterfall (SpectralTrajectory) return axe
	modified:   trajectory.py
animTraj
Added animTraj
moved animTraj to kdvOSSE/postProc module
Added .delX() to Trajectory
param input as array + .gradient() to Grid