Ciw

+ Fix bug where Individual's server isn't reset after a slotted service.

+ Allows class methods as generator functions for process-based routing.

+ Fix bug when using Mixture distribution.

+ Add a MixtureDistrubution that probabilistically chooses from a number of other distributions to sample from.
+ Baulking functions now take the simulation, current node, and current individual.
+ Service disciplines now take the current time.
+ Service disciplines now called when a customer arrives (allowing for lingering customers).
+ Distributions have parameters in their reprs.
+ Adding type hints and better doctrings.

+ Server schedules now defined with objects.
+ Slotted services feature added, with capacitated and non-capacitated slots, and pre-emption options.
+ Rename 'continue' pre-emption option to 'resume'.
+ Allows simultaneous renegeing customers.
+ Internal refactoring.

+ Fix bug where simulation errors if fist event of a node is a shift change.
+ Minor docstring and documentation changes.
+ Default statetracker is now None.