relax SVN archive

Fix for bug #18789 - the zero errors in Grace files.

This was submitted by Elio Cino <ecino att uwo dott ca> at https://gna.org/bugs/?18789.

The problem was that the errors were being taken as the X-axis error values, which in the case of
spin specific data is zero. Now the Y-axis errors are taken rather than the unused X-axis errors.
This appears to have triggered a bug in the test suite relating to Grace files with both X and Y-
axis errors.

Floats are now checked in test_bug_18789 in case the Grace format changes in the future.

Created the Relax_fit.test_bug_18789() system test for catching bug #18789.

The Grace file is written out, re-opened, and then the numbers checked.

Added the script for triggering bug #18789.

This script comes from the bug report submitted by Elio Cino <ecino att uwo dott ca> at
https://gna.org/bugs/?18789.

Added some peak list files in preparation for a system test to catch bug #18789.

This data comes from the bug report submitted by Elio Cino <ecino att uwo dott ca> at
https://gna.org/bugs/?18789.

Fix for the _minimise_data_setup method introduced at r14780.

The spin_id string needs to be stored in the data_store structure.

Fix for the GuiTestResult class with the restoration of IO redirection.

The RelaxTestResult.stopTest() method is now actually called instead of the
TextTestResult.stopTest() method.

The GUI test result classes are now being used by the GUI test suite code path.

Implemented some new classes to allow better control of the test suite from the GUI.

The GuiTestResult and GuiTestRunner classes have been added to the relax_test_runner module, and
these are used rather than RelaxTestResult and RelaxTestRunner if the from_gui flag is sent to the
main Test_suite_runner class.

The unittest _TextTestResult object is now depreciated!

All instances of _TextTestResult have been replaced by TextTestResult.