relax SVN archive

Created a short Info_box copyright string for displaying in the main GUI window.

This shows the full range of copyright dates.

Updated the copyright notices for 2016.

Copyright update for the previous commit.

Bug fix for the structure.read_pdb user function (bug #24300, https://gna.org/bugs/?24300).

When the merge flag is True, and both multiple structures and multiple models are present, the
structure.read_pdb user function would fail with a RelaxError. The problem was that the molecule
index was simply not being updated correctly.

Creation of the structure.delete_ss user function.

This simply resets the helices and sheets data structures in the internal structural object to [].

Added a check for the total argument for the frame_order.distribute user function.

The maximum value is 9999, as the PDB format cannot accept more models.

Fix for bug #24218 (https://gna.org/bugs/?24218).

This is the incorrect labelling of alignment tensors by the align_tensor.matrix_angles user function
when a subset of tensors is specified. The logic for the labels was expanded from being only for
all tensors to handling subsets.

Update the release checklist document.

The version number at http://wiki.nmr-relax.com/Template:Current_version_relax also needs to be
updated for each release.

A number of updates for the release checklist document.

This should make it easier to replicate the full release process.

Added some unicode characters for improved formatting of the CHANGES file.