* Stacked Alignment - Use Class Constant Rather than Literal
PR #1580 defined constants for "stacked" alignment in cells.
Using those constants outside of Style/Alignment was beyond the
scope of the original PR, but I said I would get to it.
This PR replaces all uses of literal -165, and appropriate uses of
literal 255, with the named constants, and adds tests to make sure
that the changed code is covered in the test suite.
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