minimize with precondJTerm with x_bkg as guess
Modifications for cycling assimilation
maxNorm implemented (first shot)
maxGradNorm at __init__
Merge branch 'maxGrad' into TWCycling

Conflicts:
	dVar/obsJTerm.py
	dVar/precondJTerm.py
Minor correction
added normGradJ
Subclasses define _costFunc and _gradCostFunc

instead of J and gradJ
maxGradNorm is then applied in gradJ
<!> it breaks the grad test!
gradTest issue solved
precond: gradNorm compared in physical space

overloading gradJ
Error in superClass minimize calling
Merge branch 'maxGrad' into TWCycling
precondJTerm always minized from xi=0
renamed BSqrt properly xi2x

xi2x apply B_sqrt *and* add x_bkg
added label top StaticObs.plot()
brooming around