* app/paint_core.[ch]: set the fg or bg color if ctrl or alt is
held. use the new dropper cursor.
* app/cursorutil.[ch], app/gdisplay.[ch], app/rect_select.c: Use
GimpCursorType enum values > GDK_CURSOR_LAST instead of seperate
functions to choose between cursor types.
* app/color_picker.c: use the new dropper cursor.
* app/paintbrush.c, app/airbrush.c, app/paintbrush.c: use the new
color picking feature of paint_core.
* cursors/dropper, cursors/droppermsk: new cursor for the color
picker tool. (this cursor is REALLY ugly, someone should fix it)
jaycox