Tests for implementing AKM constructors

[ufechner7]

Tests for #152
model = KiteModel(set) where set::Settings and KiteModel one of KPS3, KPS4, KPS5 and SymbolicAWEModel
The model struct must have the fields set::Settings and integrator and am::AtmosphericModel and iter::Int64

Also remove AbstractKiteModel, which is now defined in KiteUtils

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[ufechner7]

If you want to test it:

git checkout interface
jl
]
up
<backspace>
include("test/test_interface.jl")