relax SVN archive

Created a Clear() wizard page method for clearing a specific GUI element.

This is currently only implemented for the wizard_elements.Base_value class.

The wizard page element_string() GUI element creator read_only flag now defaults to False.

The read_only=True flag to wizard_elements.Base_value now sets a TextCtrl to the background colour.

The wizard_elements.Base_value.SetValue() method now works properly with the ComboBox.

The wizard_elements.Base_value class now can set the element to be read only.

The wizard page element_string() method now accepts all the combo box args (and a read_only arg).

Created generic_fns.pipes.PIPE_DESC_LIST which is the PIPE_DESC as a list, sorted by VALID_TYPES.

This will be used in the GUI user functions.

Better ComboBox support in wizard_elements.Base_value class.

Now strings and data are separate (if the data is supplied), and the GetValue() method now returns
the client data rather than the string value.

Modified the wizard_elements.Base_value base GUI element class to handle combo boxes.

This class can now choose between a wx.TextCtrl or a wx.ComboBox element with the element_type
keyword arg.

The Bmrb.test_bmrb_rw GUI test now uses the new execute_uf() method for the bmrb.citation uf.