Allow to use HILDON_UI_MODE_NORMAL on the HildonTouchSelector

Allow to use HILDON_UI_MODE_NORMAL on the HildonTouchSelector

* hildon/hildon-picker-dialog.c:
(selection_completed): take into account HILDON_UI_MODE_NORMAL
* hildon/hildon-touch-selector.c
(hildon_touch_selector_init): Initialize hildon-ui-mode
(hildon_touch_selector_row_activated): new callback for the
"row-activated"	signal, in order to save the last activated
(hildon_touch_selector_check_ui_mode_coherence): new method that checks
if the current hildon-ui-mode is coherent with the touch selector
(hildon_touch_selector_class_init)
(hildon_touch_selector_get_property)
(hildon_touch_selector_set_property)
Added "hildon-ui-mode" property
(disconnect_model_handlers): renamed to clean_column
(hildon_touch_selector_remove): use clean_column function
(_create_new_column): use the hildon-ui-mode to create the treeview, and
only select the first element on HILDON_UI_MODE_EDIT
(hildon_touch_selector_column_init): Initialize last_activate
(hildon_touch_selector_append_column): check that the touch selector
is coherent with the current hildon-ui-mode
(hildon_touch_selector_get_hildon_ui_mode)
(hildon_touch_selector_set_hildon_ui_mode)
Added a getter/setter for the hildon-ui-mode property
(hildon_touch_selector_get_last_activated_row): Added this method in
order to get the last activated row
* examples/hildon-touch-selector-normal-mode-example.c
New example, that shows how to use the HildonTouchSelector in
HILDON_UI_MODE_NORMAL

Fixes: NB#95685 (Add field dialog should use HILDON_UI_MODE_NORMAL), using
Kristian Rietveld <kris@lanedo.com> advices