* src/cmd-edit.c (cmd_paste): Call wb_control_paste_from_selection
without 'time' parameter.
(cmd_paste_to_selection): Call cmd_paste without 'time' parameter.

* src/item-cursor.c (item_cursor_do_action): Remove 'time'
parameter. Call cmd_paste without 'time' argument.
(context_menu_hander, item_cursor_do_drop): Call
item_cursor_do_action without 'time' argument.

* src/gui-clipboard.c
(x_clipboard_to_cell_region): Renamed from
x_selection_to_cell_region.
(x_clipboard_received): Renamed from
x_selection_received. 'widget' parameter replaced with
'clipboard', and 'time' parameter dropped. Call
gtk_clipboard_request_contents instead of gtk_selection_convert.
(x_clipboard_get_cb): Renamed from x_selection_handler. 'widget'
parameter replaced with 'clipboard', and 'time' parameter dropped.
Don't trust 'info' parameter. Gtk bug?
(x_clipboard_clear_cb): New function. Replaces x_selection_clear,
but even simpler.
(x_request_clipboard): Call gtk_clipboard_request_contents instead
of gtk_selection_convert.

* src/workbook-control.[ch], src/workbook-control-priv.h: Remove
'time' parameter from paste_from_selection method.

* src/workbook-control-component.c (wbcc_claim_selection): Remove.
(workbook_control_component_ctor_class): Inherit claim_selection
from superclass.

* src/workbook-control-gui.c (wbcg_paste_from_selection): Remove
'time' parameter and call x_request_clipboard without 'time'
parameter.
(wbcg_claim_selection): Replace old implementation with call to
new function x_claim_clipboard.
(workbook_control_gui_init): Remove call to
x_clipboard_bind_workbook.