Require explicit opt-in for "clicking grid row checks box" feature

sometimes it makes sense *not* to enable that, in which case disabled
probably should be the default

tailbone/templates/grids/buefy.mako

@@ -143,8 +143,10 @@
        :checkable="checkable"
        % if grid.checkboxes:
        :checked-rows.sync="checkedRows"
+       % if grid.clicking_row_checks_box:
        @click="rowClick"
        % endif
+       % endif
        % if grid.check_handler:
        @check="${grid.check_handler}"
        % endif