* 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.
This introduce a helper class that should be used to log things,
avoiding a lot of boilerplate code.
Also all output are made in /tmp folder instead of beside the script
itself. This is because there is a high chance that the folder containing
the script is not writtable by webserver. So using the /tmp folder
makes it more likely to works in a variety of setup.
oleibman
Adrien Crivelli