(Internal) Helper function for accessing algorithms in LEMON solver

## Usage

`LEMON(algorithm = "CycleCancelling")`

## Arguments

- algorithm
LEMON algorithm to use. Choices are "CycleCancelling",
"CapacityScaling", "CostScaling", "NetworkSimplex". Default is
"CycleCancelling".

## Value

String of the form "LEMON.<algorithm>"