Introduce spmv which calls spmv_csr

It also works a little bit faster
I don't really understand the meaning of this file, but it works
Update spmatfuncs.c
Hopefully every spmv is changed properly
use spmv or spmv_csr
forgot to import spmv_csr in mcsolve.py
Update codegen.py I'm not sure about it.
Merge pull request #57 from Vutshi/patch-8

Introduce spmv which calls spmv_csr