scalarization in spatial code

[isaacsas]

Since tests are now passing and I am not that familiar with the code, I haven't updated any spatial related codes to remove scalarization of parameters in #1052. This should probably be fixed up at some point though for consistency.

[TorkelE]

I'll have to have a think at whether this actually matters to the spatial code at all, since it just considers models after they are created. Either case I should add some tests to ensure that this is the case.