improve printing speed

[walkingeyerobot]

From a conversation with gfalcon:

So you know right now how you output N bytes, wait for M seconds, and loop? So the time was based on the max RS232 speed the printer supported (figuring it must work at least that fast)
Well, our testing with a big file showed it getting about the first kilobyte of data before cutting off
I bet if you started by sending the first 700 bytes or so in one chunk, and then did the rest throttled, you would not have that halting start in printing