Test that the spindle speed limits from the INI are honoured. 
Tests three spindles, to ensure that multi-spindle is supported

The test starts from the test.sh script which loads linuxcnc, passing it an almost-standard INI file. 
In place of the normal GUI the INI file loads test-ui.py which does not create any GUI elements. 

test-ui.py puts LinuxCNC in a condition where is can respond to MDI commands, and then proceeds to use
both MDI and the Python command interface to set various spindle speeds and check that the HAL and status
outputs are within the specified limits. 

The test-ui script then exits, and at that point the runtests script automatically runs "checkresult". 
"checkresult" is needed to skip automatic testing of "expected" againsts "result" which wouldn't
work fot this test. 

Spindle.0 has limits for MAX_FORWARD, MIN_FORWARD, MAX_REVERSE and MIN_REVERSE
Spindle.1 has no MIN_REVERSE to test that MIN_FORWARD is applied in reverse
Spindle.2 has no MIN_REVERSE or MAX_REVERSE to test that both *_FORWARD limits are applied in reverse

Spindle commands through both G-code (via MDI) and Python interface are tested. 

FIXME (?)
spindle commands through halui are not tested
spindle commands through linuxcncrsh are not tested. 
