relax SVN archive

Created an initial Structure.test_pca system test.

This executes the new structure.pca user function, and checks if data is stored in cdp.structure.

Updated the Gromacs PCA results for the newest Gromacs version (5.1.1).

Added the Gromacs PCA results for the distribution.pdb file.

This includes a script used to execute all parts of Gromacs and all output files.

The structure.pca user function now creates graphs of the PC projections.

This includes PC1 vs. PC2, PC2 vs. PC3, etc.

Modified the assemble_structural_coordinates() method to return more information.

This is from the pipe_control.structure.main module. The 'lists' boolean argument is now accepted
which will cause the function to additionally return the object ID list per molecule, the model
number list per molecule, and the molecule name list per molecule.

Added the 'format' and 'dir' arguments to the structure.pca user function.

This is to the front and back ends.

The PCA values and vectors, and the per structure projections are now being stored.

This is in the structure.pca user function backend in the pipe_control.structure.main module.

The PCA analysis function in the relax library is now returning data.

This includes the PCA values and vectors, and the per structure projections.

The PCA analysis in the relax library now calculates the per structure projections along the PCs.

Implemented the SVD algorithm for the PCA analysis in the relax library.

This simply calls numpy.linalg.svd().