change "offset" to "rise"

change "offset" to "rise"

2000-11-14  Havoc Pennington  <hp@pobox.com>

* gtk/testtextbuffer.c (fill_buffer): change "offset" to "rise"

* gtk/gtktexttypes.h (GTK_TEXT_UNKNOWN_CHAR): Add macro for
unknown char, no real reason we were using a variable.
Remove gtk_text_unknown_char variable. Fix all the text widget
files accordingly.

* gtk/gtktexttypes.c: Change "unknown character" to 0xFFFC,
since the Unicode spec seems to prefer that character for our
purposes.