Use block parameter syntax for all generators requiring one element from a list.

[Ayfri]

For example, DensityFunctions are currently created with the following code:

densityFunction("my_density_function", abs(2.0))

It will be refactored as this:

densityFunction("my_density_function") {
    abs(2.0)
}

Maybe investigate if it should throw an error if multiple functions for setting the type are used.

This will allow namespaces to be use simpler as every parameter of the Generator are usable from the lambda.

[Ayfri]

Or use the same syntax as what's currently used by recipes generator:

densityFunctions {
    abs("my_density_function", 2.0)
}
val myDensityFunction = densityFunctionsBuilder.abs("my_density_function", 2.0)