Implement a sparse matrix container and an unstructured grid for LibGeoDeco

by Christopher Bross for The STE||AR Group

I'm planing to extend the functionality of the LibGeoDecompi[1] to handle irregular grids and graphs. Therefor I want to implement a new unstructured grid class derived from the BaseGrid. To save the adjacent information I want to introduce a sparse Matrix container based on the SELL-C-σ format for efficient access and memory usage on SIMD units. [1] http://www.libgeodecomp.org