Double-click + drag to select multiple words

This patch reverts part of cb095be0cc to
allow again to double-click and then drag to select multiple words.

With this patch, the primary selection is still not updated until you
release the mouse's left button, but the selection does not "block" on
the first word while trying to double-click and drag.

I believe this behaviour has come to be expected by users, since GNOME
Terminal, Terminator, xterm, rxvt, major browsers, LibreOffice, and many
more significant applications have it.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>

kitty/mouse.c

@@ -321,7 +321,7 @@ multi_click(Window *w, unsigned int count) {
     }
     if (found_selection) {
         screen_start_selection(screen, start, y1, false, mode);
-        screen_update_selection(screen, end, y2, true);
+        screen_update_selection(screen, end, y2, false);
     }
 }