Changing CalCommands structures to make use more calculation functions

[HungGarriiix]

Currently, CalCommands directly uses CalculatorProcessor to calculate results. This prevents CalCommands to use other functions such as saving ICals, viewing history, etc. from the main operation base like CalculatorMain. CalCommands needs to use CalculatorMain instead of CalculatorProcessor.

[HungGarriiix]

Changed CalCommands from using CalculatorProcessor to CalculatorMain for expansion (refer to d2a45fd). However, on each platform (Windows form and Discord), it is designed to be used by 1 user only. Perhaps the CalCommands needs another way to maintain a collection of CalculatorMains.