The class for description of firms

Contains number of firms, costs
Revert "The class for description of firms"

This reverts commit 2b02cad7341166d440ae352c8b286f79ef0d2dda.
The class for description of firms

Contains number of firms, costs
The class for description market structure

Contains demand, firms, type of competition, order of turns (for
dynamic games).
Methods: solve