Library API rework - Githubissues

Scheduler is completely removed in favor of plain module functions mp::lpt and mp::bnb
Module alg is replaced by mp and mp_pmtn which stand for multiprocessor scheduling and mp with preemption, respectively
Schedule is simplified and custom to each module (for instance preemption uses different output structure)
The library defines typeclass Time which generalizes processing (and other) times to any numeric type with total ordering (i.e. not just floats)
There's a blanket implementation of Time for OrderedFloat and NotNan types from the ordered_float crate
There's new module mp_pmtn with an implementation of McNaughton's algorithm for P|pmtn|C_max

Algorithms currently do not use linear sorts
BnB now uses sound lower bound that's based on a modified version of McNaughton's algorithm
BnB currently does not use a priority queue to implement a variant of Best-first search
Tests are implement as unit tests (i.e. to individual modules) and mostly use rstests

Proper error reporting (currently the resulting Schedule is simply wrapped in an Option context)
Re-introduction of additional information in the scheduling result (stats, approximation factor)
Linear sort for large enough inputs for LPT and other
Queue prioritization & other heuristics for BnB
Benchmarks rework using criterion (currently does not even compile due to unstable feature(test) macro)

matyama / makespan