relax SVN archive

Shifted the lib.opendx package to lib.software.opendx.

Missing import fix for the lib.alignment.alignment_tensor module.

Shifted and decoupled some of the grace code into lib.software.grace.

This includes most of the write_xy_header() and write_xy_data() functions. The data store specific
part of write_xy_header() has been shifted into pipe_control.grace.axis_setup().

Created the empty lib.software package.

This will be for functions which create input, read output, or control external programs.

Shifted some of the pipe_control.diffusion_tensor functions to lib.diffusion.main.

Shifted calc_chi_tensor() and kappa() from pipe_control.align_tensor to lib.alignment.alignment_tensor.

The frame order analysis is now using the correct centre of mass function.

Speed ups for the interatom_loop() by restoring some of the code deleted at r19149.

This spin ID lookup table is being used again, as this is much faster than the string parsing of
spin IDs.

Restored the selection object __contains_spin_id() method as contains_spin_id().

This will allow for faster checks for matches to spin ID strings.

Fix for the pipe_control.relax_data.pack_data() function for the selection object changes.