[FIX] Error when selecting filters in calendar view

e.g. calendar view of customer invoice

Also attempted to make the code flow slightly simpler by just forcing
the filter to a [value, label] pair in all cases.

bzr revid: xmo@openerp.com-20130516125650-qeqx97dzzhzjrq52

diff --cc addons/web_calendar/static/src/js/calendar.js
index fdc2f94,66d2b67..2e12ddc
--- 1/addons/web_calendar/static/src/js/calendar.js
--- 2/addons/web_calendar/static/src/js/calendar.js
+++ b/addons/web_calendar/static/src/js/calendar.js
@@@ -265,8 -265,8 +265,9 @@@ instance.web_calendar.CalendarView = in
          //To parse Events we have to convert date Format
          var res_events = [],
              sidebar_items = {};
--        var selection_label = {};
++        var selection_label;
          if(this.fields[this.color_field].selection) {
++            selection_label = {};
              _(this.fields[this.color_field].selection).each(function(value){
                  selection_label[value[0]] = value[1];
              });
@@@ -280,16 -280,16 +281,19 @@@
              if (this.color_field) {
                  var filter = evt[this.color_field];
                  if (filter) {
--                    if(this.fields[this.color_field].selection) {
-                         filter = selection_label[filter];
 -                        filter = (typeof filter === 'object') ? selection_label[filter[0]] : selection_label[filter];
++                    if (typeof filter !== 'object') {
++                        filter = [filter, filter];
                      }
--                    var filter_value = (typeof filter === 'object') ? filter[0] : filter;
++                    if (selection_label) {
++                        filter[1] = selection_label[filter[0]];
++                    }
++                    var filter_value = filter[0];
                      if (typeof(fn_filter) === 'function' && !fn_filter(filter_value)) {
                          continue;
                      }
                      var filter_item = {
                          value: filter_value,
--                        label: (typeof filter === 'object') ? filter[1] : filter,
++                        label: filter[1],
                          color: this.get_color(filter_value)
                      };
                      if (!sidebar_items[filter_value]) {