implemented tridiagonal solver.
Implemented cyclic tridiagonal solver.
More implementation, but untested.
finished the metapath solver, but untested.
Metapath bug fixes.
Sqashed most bugs (hopefully).
Added metapath.
Added type signature.
Added metapath.
More documentation and bug fixes.
Lingering trace removed.
Changed metapath datatype.
Merge branch 'metapath'