For some reason a portYIELD() is not enough to give the serial task the
option to run. I tried vTaskDelay() and that works. To not block more than
needed portYIELD() is still called when the queue is not full and only
call vTaskDelay() when it is full.

Closes #218

Closes #217

See merge request !421

The MSC interrupts can come in back to back, effectively blocking
the FreeRTOS timer task which resets the watchdog. This simple fix
simply resets the watchdog when performing an MSC read or write.

See merge request !419

See merge request !414

The -EIO error was triggering a warning in the caller.

Make private functions static
Allocate buffers on stack
Move constants out of header

Pycardium Improvements

Closes #76 and #212

See merge request !417

This will result in more reliably reaching a clean state.

Co-Authored-By: schneider <schneider@muc.ccc.de>
Signed-off-by: Rahix <rahix@rahix.de>

See merge request !418