a litle more stability in svigp

Another instance of dpotrs instead of dot
BGPLVM still failing, doesn't seem to be numerical : (
pdinv passes extra args to jitchol
demo changed, bgplvm still broken
Merge branch 'devel' into mrd
xticklabels improved
Merge branch 'devel' of github.com:SheffieldML/GPy into devel
made the basic GP class use dtrtrs where possible
GPy now fails silently if sympy is not present
Nparam_transformed work better now

Before, counted the number of fixes, which failed when a fix fixed more
than one parameter...
added a kernel for independent outputs
prod_orthogonal now caches the K matrices
fixing small bug in independent outputs kern
more minor bugs
fixed a weird regular expression bug in ensure_def_constraints
psi stat tests
merge devel mrd
Revert "merge devel mrd"

This reverts commit 3f625a9347fde47625f14898c0a3a6ed4f49b55a, reversing
changes made to dc6faeb30355bf9c6f0f3694e8546bcdf26372a8.
psi stat tests done and failing gracefully
Merge branch 'mrd' of github.com:SheffieldML/GPy into mrd