An S4 class to represent scenario settings

Class 'settings' inherits all slots from class 'config' and adds the following:

Slots

subset: list. Named list of subsets used in the model. The names of the list elements are the names of the subsets, the values are the vectors of the subset elements. The subsets are used to narrow the dimension of the model variables and constraints.
yearFraction: numeric. The fraction of a year covered by the calendar, e.g. 1 for annual calendar (default), 0.5 for semi-annual, 0.25 for quarterly, etc. Currently must be specified manually for subset calendars to validate the sum of the shares.
solver: list. Named list of solver parameters. The names of the list elements are the names of the solver parameters, the values are the solver parameters themselves. The solver parameters are used to control the optimization process.
sourceCode: list. Named list of paths to the source code files. The names of the list elements are the names of the source code files, the values are the paths to the source code files. The source code files are used to store the model and scenario scripts.