There were two classes named TestArrayPriority in test_multiarray.py,
both of which tested the use of the __array_priority__ attribute.
Because the later addition tests more functions than the earlier one and
for more dtypes, the earlier version is removed.

Many of these fixups are result from removing `from x import *`
imports. The rest are mostly unused variable fixes.

The dot tests in test_numeric have not done anything useful since the
_dotblas module was merged into multiarray. There used to be two
potentially different dot functions, one from _dotblas and the other
from multiarray, that the tests compared against each other. Because
both functions are now the same that no longer serves any purpose, so
those tests have been modified to check against known results and moved
into test_multiarray with the other dot tests.

The dot tests could use improvement. They don't check all the types,
exceptions, and such. But fixing them exceeds the scope of the present
work.