In adcall.py the pyb module may not be imported, so use ADCAll directly.
In dac.py the DAC object now prints more info, so update .exp file.
In spi.py the SPI should be deinitialised upon exit, so the test can run a
second time correctly.
In tests/pyb is now a suite of tests that tests the pyb module on the
pyboard. They include expected output files because we can't run
CPython on the pyboard to compare against.
run-tests script has now been updated to allow pyboard tests to be run.
Just pass the option --pyboard. This runs all basic, float and pyb
tests. Note that float/math-fun.py currently fails because not all math
functions are implemented in stmhal/.
