New module to synchronously, blocking send gcodes with return

[volconst]

Implement the ping pong protocol - wait for 'ok' after each command, so no commands are lost with possibility to parse printer response specifically for each command. Related to #986 #959 #990 #965

[kliment]

This is great, thanks for contributing it! Are you still working on it or should I merge it as is?

[volconst]

Hi @kliment
I have no experience with managing pull requests, even thought that they are fixed at creation time.
So I am open to advice should I open several pull requests at once and when to seek your attention.
I prepared PR #1009 which is single feature and complete, you can merge it.
Current PR #1008 turned to contain several unrelated changes and it's title is not relevant to all the commits. I think it should not be merged now, but we can discuss the commits here.

2572052 This commit is both a library and a sample for the ping pong protocol. I have based on it a console script for manual bed leveling, which moves nozzle with the arrow keys, but I am not sure if I will publish it.

7d001ae
I need feedback on this. Does it work on Windows? This is the most controversial commit. May put garbage on the command line, but I like the dynamic temp update. It is not good design to block in the main thread in readline raw_input and to update the prompt in the serial thread, but the default python readline library is not providing non blocking API. I think there should be loop select([serial, keyboard]) and then react accordingly. And maybe use curses.tparm(tigetstr("cup"), 5, 3) for the control sequences.
Thank you