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Changelog
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Version 2.0
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- New implementation of freezing model for a single container with spatial resolution (termed snowing). The model considers the gradients in temperature and in ice mass that form during freezing. 
- Currently supported features of the new spatial model:
    - Simulation of three different freezing process configuration:
        - Shelf-ramped freezing (commonly used in freeze-drying)
        - Vacuum-induced surface freezing (process variation where vacuum is applied to promote freezing through surface evaporation)
        - Jacket-ramped freezing (process variation where vial is surrounded by a temperature-controlled jacket
    - Simulation of different heat transfer boundary conditions (natural convection, conduction, thermal radiation, surface evaporation)
    - Simulation with different dimensionalities (0D, 1D, 2D)


Version 1.1
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- Support for 3D configurations, i.e. the arrangement of vials in three spatial dimensions. The package thus may be used to simulate the freezing of vials for storage in pallets, a common process in the manufacturing of biopharmaceuticals
- Enhancements:
    - Initial Temp of vials can now be set independently (used to be defined by operating condition)
    - Fixing a minor bug where freezing point depression was not considered
    - Implementation of second numerical approach to compute the initial amount of ice formed upon nucleation
    - Allow for cooling rate of 0
    - Additional warnings if holding and cooling times exceed the total time
    - Vial group 'center' is going to be deprecated in favor of 'core' (also: new type 'side' was added for 3D)
    - Other, minor bug fixes

Version 1.0
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- Implementation of freezing model for the freezing stage in freeze-drying of a batch of vials on a shelf in python
- Currently supported features: 
    - Simulation of the freezing process, i.e. of thermal evolution and of ice formation, for a batch with arbitrary number of vials
    - Arbitrary cooling protocols (i.e., user may choose cooling rate, integrate holding steps and controlled nucleation)
    - Tracking of nucleation times, nucleation temperatures and solidification times for all vials
    - Stochastic nucleation in the form of a Monte Carlo approach as well as controlled nucleation in the form of forced initiation of nucleation at a certain point 
    - Cubic geometry of vial and rectangular arrangement on the shelf
