WIP
WIP
Added new model tests and restructured tests
Changed place of SymPyModels.ipynb
Fixed SciPy dependency in TestParametricModel
Fixed Docstrings of TrapezoidModels and added 'See Also' section
Fixed Docstrings of Airy2DModel
Docstring fixes MexicanHat1D
Added contraints keyword argument to models
Extended model tests
Fixed Scipy error in model tests
Fixed Scipy error in model tests
Fixed SciPy error 2
Fixed SciPy error 2
Modified to work with 2D derivatives
Added Beta1D and 2D models
Added Beta models and some explanation
Added input test and fixed comments
Added Beta models
Made polynomial work with NonLinearFitter