relax SVN archive

Another fix for the bug of sr #2764 (https://gna.org/support/?2764).

The sequence file variable is in self.data!!!

Fix for the bug reported as sr #2764 (https://gna.org/support/index.php?2764).

The problem was that the sequence file is now in the variable sequence_file.

Added support for old save files in the Peak_intensity.sync_ds() method.

The structure.read_pdb graphic is now used in the user function.

Created a graphic for the structure.read_pdb user function window.

The description section of the wizard page now scrolls if greater than a given number of pixels.

This uses a scrolled panel and only scrolls if the text is too long.

Decreased the size of the structure.read_pdb user function window.

Created the structure.read_pdb GUI user function window and menu entry.

Added the structure relax icon to the paths module.

Fix for the 16x16 structure icon - it was the original full-sized graphic!