port LUDecomposition(base + alt) to AltLU
add lu decomposition base tests
add lu decomposition alt tests
port LinearSolverLU to LUSolver
add tests for LUSolver
Merge branch 'develop' of github.com:mikera/vectorz into lu_solver
add least squares for AMatrix in API
return null when no solution, add API tests
add docs
Merge pull request #57 from prasant94/lu_solver

Lu solver + tests