Update 30-may-2013

Update:
- Everything required by the assignment is done except the bonus part
(CREDITS) and plots and passing parameters from command line
- Conjugate gradient and Gauss Seidel are both implemented.
- Changes in the data structure.

Problems:
- eigenvalue is slightly smaller than the reference result, which of
course leading to eigenmode.txt slightly different than the reference
file. It could be the compiler or compling option I am using. I will
test it in the computer lab tomorrow
- for large value of epsilon (greater than 0.00001), the solution does
not converge