Change extension of Wire examples, .pde to .ino

...aries/Wire/examples/SFRRanger_reader/SFRRanger_reader.ino

.../examples/digital_potentiometer/digital_potentiometer.ino

libraries/Wire/examples/master_reader/master_reader.ino

libraries/Wire/examples/master_writer/master_writer.ino

libraries/Wire/examples/slave_receiver/slave_receiver.ino

libraries/Wire/examples/slave_sender/slave_sender.ino