parameters gridding with checkgrad to aid debugging
Merge branch 'master' of github.com:SheffieldML/GPy into debug
some code to debug the sprase GP gradients with.
allowed the gradchecker to return the gradient ratio

Just to help with debugging.
plotting changes
changed the colous of plotting in the grid_parameters debug script
simplified the debug classes
fixed up dK_dX in the exponential and Matern kerns
general changes to bebugging code
Scale factor added to sparse_GP_regression

and sparse_GP_demo ammended to be less annoying (m1)
fixed optimize_restarts
various hackday stuff, including scale factor in sparse GP
minor changes to the apsre regression demo
decent gradients for most parameters
BGPLVM working with rbf+white
BGPLVM working
new shape for psi2
broken commit, working on cross terms for psi statistics
working on cross terms
trying to get psi2 cross terms to work