Using an Integrate() function

[Balavarun5]

commit : ba250f5

Description

This code doesn't use the Lobatto quadrature using the same number of LGL points used to obtain the Lagrange basis polynomials, The shortcomings of this are shown in Issue #13

Motivation

As seen in Issue #6 , The 1D wave blows up with time. To resolve this, all integration terms in the code were refactored to use an Integrate() function which takes in the analytical form of the integrand and can use either Gaussian or Lobatto quadrature.

Possible implementation

The code in ba250f5 uses this Integrate() function and unit tests for volume Integral flux and A matrix were passing.