Feeder is not sending lines when requested by the table

The feeder class is checking if the drawing device is asking for lost lines but for some reason is not able to send them back correctly

With this commit the "resend" request is fulfilled correctly. Still there are some performance issues with very intricate geometries/lot of close points

Should check the lenght of the buffer before releasing the lock here?

sandypi/NCFeeder/feeder.py

Line 223 in 6067ce7

self.command_send_mutex.release()

Should check the lenght of the buffer before releasing the lock here?

sandypi/NCFeeder/feeder.py

Line 223 in 6067ce7

self.command_send_mutex.release()

Fixed some problems but still not a solution... May have problems with serial speed... May try to read before sending:

sandypi/NCFeeder/feeder.py

Line 374 in dea56f3

self.serial.write(str(obj).encode())

Should be fixed in #17