Calendars and PE data types

NEW SF_CALENDAR() function for "economic", "earnings", "dividends" and "splits" calendars.

NEW US Treasury Rates using SF_CALENDAR() function.

NEW "insiders" data type for insider trading roster data.

NEW "insidersStats" data type for summarised insider trading statistics.

NEW "sectorPE" data type for historical average sector PE ratios.

NEW "industryPE" data type for historical average industry PE ratios.

Bug fixing.