* src/workbook-control-gui.c (wbcg_sheet_add): Make the
	GNUMERIC_SHEET target GTK_TARGET_SAME_APP.
	(cb_wbcg_drag_data_received): Added source_widget parameter.

	* src/sheet-object.c (sheet_object_rubber_band_directly): Always
	return FALSE.

	* src/gnumeric-pane.c (drag_types_in, drag_types_out):
	New. Supported drag targets.
	(cb_pane_drag_data_received): Pass source widget to
	scg_drag_data_received.
	(cb_gnm_pane_drag_data_get): New. drag-data-get callback.
	(cb_gnm_pane_drag_motion): New. drag-motion callback.
	(cb_gnm_pane_drag_leave): New. drag-leave callback.
	(gnm_pane_drag_dest_init): New. Factor out of gnm_pane_init and
	Connect drag-data-get, drag-motion and drag-leave callbacks.
	(gnm_pane_init): Use it.
	(gnm_pane_objects_drag): New. Factored out of gnm_pane_object_move.
	(gnm_pane_object_move): Use it.
	(cb_test_so_imageable): New. Check if object is imageable.
	(gnm_pane_drag_begin): New. Start gtk drag.
	(cb_control_point_event): Use it.

	* src/sheet-control-gui.c (scg_paste_cellregion): New. Paste
	a cellregion.
	(scg_drag_receive_cellregion): New. Receive a dropped cellregion.
	(scg_drag_receive_uri_list): New. Receive a dropped uri list.
	(scg_drag_receive_same_scg): New. Receive a drop from same scg.
	(scg_drag_receive_same_proc_other_scg): New. Receive a drop from
	another scg in same process.
	(scg_drag_receive_same_process): New. Receive a drop from this
	gnumeric process.
	(scg_drag_data_received): Added source_widget parameter. Handling
	of each target moved to a separate function. Added support for gnumeric
	gtk clipboard format. Added support for process internal dnd which
	shortcuts the selection.
	(scg_drag_send_image): New. Send an image over the dnd selection.
	(scg_drag_send_clipboard_objects): New. Send selected objects over
	the dnd selection. Gnumeric gtk clipboard format is used.
	(scg_drag_data_get): New. Send selected objects over the dnd
	selection in requested format.