This is an update of gtk-mailund-980720-0, which adds user data to
text properties in gtktext, thus making it possible to associate
arbitrary data to sections of the text. This can be useful when
e.g. associating links from parts of the text to other parts or other
files (html links, comments which can be hidden/show with
double-clicks etc.).

The changes for this patch is:

 * TextProperties is hidden in the .c file.  Access to properties goes
   through functions, called with an integer as argument.  This
   integer is used as a position in the text, and the functions
   operates on the property at that position.

 * The functions installed in GtkText for handling the user data is
   now accessed through a function.

 * The set_property function freezes/thaws GtkText.

/mailund