Cholesky Decomposition Tiled Algorithm

The implementation of Cholesky Decomposition Tiled Algorithm for S-Net described by Buttari et al. [1]

The implementation consists of
* Coordination network definition
* Implementation of main algorithms and supplimentary boxes
    - Initial Factorization (`compute_s1.c`)
    - Triangular Solve (`compute_s2.c`)
    - Symmetric Rank Update (`compute_s3.c`)
* Sample input data (`data.xml`, `data2.xml`)
* Input data generator. The script generator.py takes three input arguments (N - a dimension of the matrix, BS - a size of a block and a prefix for the file name) and generates a file with input data `prefix_snet_in.xml` and file with output data `prefix_snet_out.xml`. `prefix_snet_out.xml` contains only aproximations of correct values because of the floating point. The sample output can't be compared literally to the actual output.
  ```
  generator.py 512 16 foo
  ``` 
  will create files `foo_snet_in.xml` and `foo_snet_out.xml` where input matrix is a generated 512x512 matrix and the size of the block will be 16.
  
  IMPORTANT: The application was tested only with sizes which are power of two.

* Test script `test.sh`. The script generates input matrices of different size and output the execution time suitable for plotting.

[1] Kurzak, J.; Buttari, A.; Dongarra, J., "Solving Systems of Linear Equations on the CELL Processor Using Cholesky Factorization," Parallel and Distributed Systems, IEEE Transactions on , vol.19, no.9, pp.1175,1186, Sept. 2008