Clear display on serial monitor

[johnerrington]

Could we move this to the IDE2 section as a suggestion?

@xfpd

The IDE protests the unknown (unsupported) escape sequences.

C:\...\sketch_mar12a.ino:4:16: warning: unknown escape sequence: '\h'
   Serial.print("\h");
                ^~~~
C:\...\sketch_mar12a.ino:5:16: warning: unknown escape sequence: '\j'
   Serial.print("\j");
                ^~~~