If a heater falls out of the target range, accumulate the temperature
differences to determine if an error should be raised. This should
make it less likely to report an error for heaters that drift slightly
out of range, and it should make error reporting faster for heaters
that rapidly fall out of range.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
A default of 4 degrees and 10 seconds may be too aggressive - change
the default to 10 degrees and 15 seconds.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>