relax SVN archive

Created the Peak_lists.test_read_peak_list_sparky_double system test.

This is used to test the loading of multiple files simultaneously by the spectrum.read_intensities
user function.

Continued expanding the tutorial for performing a relaxation dispersion analysis in the GUI.

This is for the dispersion chapter of the manual.

More modifications to the sequence input GUI window to match the multiple file selection element.

The window now starts with a single element rather than nothing.

Removed a debugging printout statement accidentally committed at r22235.

Added a 'Delete' button to the sequence input GUI window.

This is to match the multiple file selection GUI window. The button allows the user to delete the
last item from the list. So if 'Add' has been clicked too many times, the user does not have to
start again from scratch by clicking on 'Delete all'.

Modified the GUI window for inputting sequence data to include item numbers.

An non-editable initial column with the number of each item has been added. This is to help the
user when, for example, the items of one sequence element should match another (for example in the
spectrum.read_intensities user function where multiple file names should match multiple spectrum
IDs).

Fixes for the unit tests of the spectrum.read_intensities user function.

A number of checks were not correctly set up, and the recent changes caused others to now fail.

Created the test_loop_exp_frq() dispersion unit test.

This checks the operation of the loop_exp_frq() function from the module
specific_analyses.relax_disp.disp_data. It uses the data attached to the bug report at
https://gna.org/bugs/?21665.

Renamed the test_loop_exp_time() dispersion unit test to test_loop_exp_frq_offset_point_time().

This is for the specific_analyses.relax_disp.disp_data.Test_disp_data.test_loop_exp_frq_offset_point_time()
unit test. The name better reflects the function being tested.

Small spacing fix.