* glom/libglom/utils.[h|cc]: Added build_simple_where_expression()
    and build_combined_where_expression() to make it easier to work with
    Gnome::Gda::SqlExpr.
    build_sql_select_with_key(): Return a SqlExpr instead of a string.
	* glom/base_db.[h|cc]:
	* glom/base_db_table_data.cc:
	* glom/frame_glom.[h|cc]:
	* glom/libglom/data_structure/foundset.[h|cc]:
	* glom/mode_data/box_data.[h|cc]:
	* glom/mode_data/box_data_calendar_related.cc:
	* glom/mode_data/box_data_details.cc:
	* glom/mode_data/box_data_list.cc:
	* glom/mode_data/box_data_portal.cc:
	* glom/mode_data/datawidget/dialog_choose_id..[h|cc]:
	* glom/mode_find/notebook_find.[h|cc]:
	* glom/print_layout/canvas_print_layout.cc:
	* glom/report_builder.cc:
	* glom/utility_widgets/db_adddel/glom_db_treemodel.cc:
    Adapt, using SqlExpr instead of a string for where clauses.