#4 Refactoring: buffered console output

[Andrey B]

We need to package buffered output currently implemented in datalogging as ChibiOS/RT stream so that printf could be used code could be simplified.

[Andrey B]

Could help: http://forum.chibios.org/phpbb/viewtopic.php?f=3&t=1431

[Andrey B]

This is about

    resetLogging(&signal->logging);
    append(&signal->logging, "msg");
    append(&signal->logging, DELIMETER);
            appendInt(&signal->logging, now - signal->last_scheduling_time);
    append(&signal->logging, " ticks ago ");
    scheduleLogging(&signal->logging);

Which we need because we are not allowed to print directly to console in interupt handler context.

The first step of improving this nightmare would be
printbuffered(&signal->logging, "msg;%d ticks ago", now - signal->last_scheduling_time);

Later we might consider changing the primary 'print' implementation so that it checks current context dynamically and uses the same shared buffer for output (see isIsrContext()), but that's a separate story.