Version changes

• Week numbers
• Interval for minutes
• Tooltips (also popup based tooltips)
• getCellDimension
• onMouseOver / onMouseOut events
• onPopupShow / onPopupHide events
• onShow / onHide events
• Basic double-calendar functionality

Notable changes:

1. 3 supported skins: dhx_skyblue, dhx_web and omega.
   For style customization use SkinBuider.
   
   
2. There's no any header in the calendar now. For this reason, header-related functionality isn't supported anymore (e.g. setHeader() method).
   
   
3. setYearRange() method was excluded due to a new look of the year selector.
   
   
4. The list of the supported date formats was changed. See a new complete list here.
   
   
5. Double calendar is not supported.
   
   
6. New definitions of locale labels.
   
   For example, defining a new language:
   

   //3.0 version
   dhtmlXCalendarObject.prototype.langData["de"] = {
      dateformat: '%d.%m.%Y',
      ...
   }
   //2.6 version
   dhtmlxCalendarLangModules['de'] = {
      langname:	'de',
      dateformat:	'%d.%m.%Y'
      ...
   }