Cleanup and merge branches

[epsi1on]

I think it would be good to have some cleanups.
This repo have three branches:

• master
• sparse-matrix : support of sparse matrix (Support for SparseMatrix #2)
• remove-math-net: remove Math.Net dependency (Remove Math.Net dependency #7)

I think supporting of sparse-matrix is solved with introducing ILinearSolver interface in master branch (as discussed in #2). So maybe the sparse-matrix branch can be ignored and removed.
Then Review the remove-math-net and merge pull request, and then merge into master and finally project have only one update branch without Mat.Net dependency and compatible with SparseMatrix