Add Stiffness Matrix and Load Vector methods
Add Stiffness Matrix and Load Vector methods

1. A new Parent Class has been created for Triangular and Quad Class - the Shell Class. This class will allow all similar methods from Triangular and Quad elements to be combined into one parent class and therefore prevent duplication of methods.
2. Line 2 and Line3 received a new Parent Class as well - the Line Class. Same as above. This segmentation of Line and Shell will allow for another layer of separation of the methods which was required when the Line elements were introduced.

3. Line and Shell Class received two new solver. The first is a Heat diffusion and convection stiffness matrix solver and the other is the Heat convection load vector solver. I am on track to introduce more and more solvers in the future.

4. With the addition of the new solvers, I added a new method which integrates over the domain of the elements, allowing the calculation to be done on the reference elements and switching it over the real element using the jacobian matrix.
MrJarv1s/FEMur