Add SMS capability v1.0

THIS UPDATE IS NOT FULLY TESTED AND MUST NOT BE RELIED UPON FOR ACCURATE OR COMPLETE DATA DELIVERY.  IT IS FOR DEVELOPMENT AND CONVENIENCE ONLY.  THERE IS NO ALERT FOR LOSS OF DATA, SO LACK OF A TEXT MESSAGE DOES NOT MEAN THAT BG IS IN RANGE.

Uses Clickatell SMS API
Configure user preferences using lines 34-47 (Enable/disable SMS, Clickatell account info, BG low/high, alert interval)
Clears prior data on startup to avoid display of obsolete data
First reading displayed like "10:00 AM - 110 new" meaning that it is the first new data point
Subsequent alerts when BG is above or below specified values.  Alerts like "97 up 6" or "104 down 3" or "100 stable"
Alerts every "X" readings as specified in the user's configuration
Sends "No Data" when data timestamp has not been updated (intended to catch data loss - NOT TESTED).