Add new AUTO special value, resolve #20

Jan Breuer

2015-03-18 f8536daee65bdd87d004771c787a6f42a1397859

 libscpi/src/units.c

@@ -112,6 +112,7 @@
    {/* name */ "NAN", /* type */ SCPI_NUM_NAN},
    {/* name */ "INFinity", /* type */ SCPI_NUM_INF},
    {/* name */ "NINF", /* type */ SCPI_NUM_NINF},
    {/* name */ "AUTO", /* type */ SCPI_NUM_AUTO},
    SCPI_CHOICE_LIST_END,
};