New Problem: Gaussian Elimination with Partial Pivoting

[paddywardle]

I want to add a new problem on applying gaussian elimination with partial pivoting to solve a linear system of equations.

The problem will cover:

• Elimination
• Backward subsititution
• Partial Pivoting
• Implementation of gaussian elimination in NumPy

This will be a "Medium" difficulty problem in the linear algebra category.

[moe18]

all yours