Improved copy to sd, added watchExpression, added response catching to serial.js

Improved copy to sd by using chunks.
removed double call of serial.js in main.html
added catching of responses in serial.js, catches everything starting with <<<<< and ending with >>>>>
added processor named getWatched
new plugin watchExpression to handle expressions for sending to board, and display response from board
added simple tour to see what watchExpression is doing.