Update Calculator to Scientific (Basic Operations)

[sushi-trash]

Task Tests:

• Current calculator is updated so that it can perform more operations
• Check that sin, cos, tan operations are functional
• Check that exponents and square roots are functional
• Make sure that the calculations performed are accurate

[clincl]

If you can, try to add as much functionality to this as possible to we don't have to go back to the calculator later for any improvements. e.g. log;ln; n!; PI input symbol. However, what you have is good enough.