relax SVN archive

Modified the operation of openfile().

The directory is now set to getcwd(), and any moving around in the file structure in the dialog by
the user causes the current working directory to change (using chdir()).

Modified the openfile() function to match the relax conventions.

The function comments were converted to the function docstring, comments were added to the code,
and the spacing was fixed.

Missing import.

Changed the open_file() method to only change variables in its own class.

Renamed the StructureTextCtrl method structure_pdb() to open_file().

All PDB file inputs now use StructureTextCtrl.

Converted the structure_pdb() method into a method of a new class derived from wx.TextCtrl.

The new derived classes module will have wx classes modified for use in the relax GUI.

Deleted the __set_properties() method and shifted the frame font size property into __init__().

Deleted the now unused __do_layout() method.

A few unused sizers were inside this method.

Shifted a property into add_relax_data_input() that had not been already moved.