Added symbols for AD849x Thermocouple Amp

Created by: johnfwhitmore

Signed-off-by: John Whitmore johnfwhitmore@gmail.com

This is a Pull Request for the four members of the Analog Devices AD849x family of Thermocouple amplifiers.

Datasheet - http://www.analog.com/media/en/technical-documentation/data-sheets /ad8494_8495_8496_8497.pdf