A small patch to fix a few bugs in gtktext.c.
By Reed D. Meyer (rdm@astro.yale.edu), 07/11/99.

      Fixes:
         * Bug in not properly displaying text after deleting selected text.
         * If an entire line of text is selected and deleted, the new-line
           is now also deleted (before, a CTRL-U wouldn't delete the \n).
         * The cursor now remains on the selected line after selecting a whole
           line.  Before, it would skip to the beginning of the next line.
         * Lines with exactly N characters (where N is the width of the text
           window), not including the \n, do not wrap.  Before, they did,
           which was annoying if you had text formatted to exactly the width
           of the text window (e.g., 80-char fields displayed on 80-char-wide
           windows wrapped).  A minor bug remains in that if you insert chars
           enough to make the line wrap and then delete chars with the cursor
           currently at the \n, the line won't unwrap until length gets down
           to N-1, not N, characters.  Too minor to bother fixing.