relax SVN archive

Converted the RelaxError introduced in r17944 to a RelaxWarning.

There are some cases where deselection of all spins is ok, for example an analysis using the local
tm models where some models are run but skipped when they have too many parameters.

The model-free overfit deselection algorithm now fails with a RelaxError when no spins are selected.

This is to avoid situations such as bug #20277 (https://gna.org/bugs/?20277).

Fixes for the pseudo-ellipse frame order model when running in multi-processor mode.

Previously the back-calculated PCS data was not being returned from the slaves, causing the
chi-squared value to be a fixed value as the real values were always compared to zero.

Fix for the http://www.nmr-relax.com/download.html webpage.

An extra <tr> element was found by the W3C Validator
(http://validator.w3.org/check?uri=http://www.nmr-relax.com/download.html).

Fix for the MARC links at http://www.nmr-relax.com/communication.html.

This was a & to & change in the links. The problem was picked up by the W3C validator
(http://validator.w3.org).

The links are now:
http://marc.info/?l=relax-announce&r=1&w=2
http://marc.info/?l=relax-users&r=1&w=2
http://marc.info/?l=relax-devel&r=1&w=2
http://marc.info/?l=relax-commits&r=1&w=2

HTML fixes for http://www.nmr-relax.com/links.html.

The problems were detected using the W3C validator (http://validator.w3.org/).

Added the MARC archive links to the development chapter of the relax user manual.

These links are:
http://marc.info/?l=relax-announce&r=1&w=2
http://marc.info/?l=relax-users&r=1&w=2
http://marc.info/?l=relax-devel&r=1&w=2
http://marc.info/?l=relax-commits&r=1&w=2

Added the MARC archives to the http://www.nmr-relax.com/links.html webpage.

Added the relax mailing lists newly added to MARC to http://www.nmr-relax.com/communication.html.

Improvements to the Frame Order multi-processor testing script.