relax SVN archive

Modified the User_functions.test_structure_pdb_read() GUI test to catch another bug.

This is a bug recently introduced with the fixes to the other sequence editor GUI window problems.

Fix for bug #20184 (https://gna.org/bugs/?20184).

The behaviour of the gui.string_conv.gui_to_int() and related functions has changed in the last few
months and the Sequence_window() GUI element has not changed to match. This has been fixed and the
User_functions.test_structure_pdb_read() GUI test now passes.

Fixes for the User_functions.test_structure_pdb_read() GUI test.

Created the User_functions.test_structure_pdb_read GUI test for checking the sequence editor window.

This new user function GUI testing class is to be used for testing out the special GUI elements not
invoked within the unit testing. The test_structure_pdb_read() test specifically shows a number of
failures of the sequence editor window.

Modified the operation of the sequence GUI element to have access to the sequence editor window.

This is to allow this GUI element to be blasted within the test suite.

Fix for bug #20183 (https://gna.org/bugs/?20183) - the failure of the sequence editor window.

The problem was that fields which could be either single values or lists (or tuples) of values were
not properly handled.

Fix for bug #20182 (https://gna.org/bugs/?20182) - the sequence element window ordering issue.

The sequence element window now has the parent wx.Window element set. This prevents the main relax
window from being set as the parent and hence coming to the front after the sequence element window
is launched from a user function window.

Improvements to the descriptions of the structure.read_xyz user function arguments.

Improvements to the descriptions of the structure.read_pdb user function arguments.

Fix for bug #20181 - the GUI sequence editor window TypeError problem.

This is the fix for the bug reported at https://gna.org/bugs/?20181.