first attemot at the new constraint framework
improved stability of sparse GP for certain-input case
fixed has_uncertain_inputs weirdness
fixed bug in constrain_fixed where soem values weren't deleted
whitespace
Merge branch 'devel' into new_constraints

Conflicts:
	GPy/core/model.py
	GPy/core/parameterised.py
eigenvalue decomposition of psi2
added file:transformations
typo corrected for negative constrains
fixed a tie-bug for ND
Merge branch 'devel' of github.com:SheffieldML/GPy into devel
auto_scale option for heteroscedastic noise
error bars fixed
merge devel into mrd > transformations added