Restructuring output

[htjb]

It would be good if the code could output a single pickled file with the current contents of T_release/, for example, accessible with something like

emu = globalemu.load('T_release.pkl')
emu.evaluate(params)
redshift = emu.z
# etc...

This would make the output more compact and easier to share. It will require some significant editing to the code though I believe. I previously tried to do this and ran into issues where I was trying to pickle an already pickled tensorflow object but I think we can get around this in the future with a bit more thought.