* Move Gridlines from Chart to Axis
This could, I hope, be my last major change to Chart for a while. When I first noticed this problem, I thought it would be a breaking change. However, although this change establishes some deprecations, I don't think it breaks anything. Major and minor gridlines had only been settable by the Chart constructor. This PR moves them where they belong, to Axis (eexisting Chart constructor code will still work). This allows them to be specified from both X and Y axis.
Chart is now entirely covered except for 2 statements, one deprecated and one that I just can't figure out. 99.71% for Charts, 88.96% overall. All references to the Chart directory in Phpstan baseline are eliminated.
* Minor Fixes, Unit Tests
Line style color type should default to null not prstClr.
Chart X-axis and Y-axis should alway be Axis, never null.
Add some unit tests.
* More Tests, Some Improvements
Make it easier to change line styles, adding an alternate method besides a setter function with at least a dozen parameters.
* Add Support to Chart/Axis and Gridlines for Shadow
Continuing the work from #2865. Support is added for Shadow properties for Axis and Gridlines, and Glow and SoftEdges are extended to Gridlines. Tests are added. Some chart tests are moved from Reader/Xlsx and Writer/Xlsx so that most chart tests are under a single directory.
This is a minor breaking change. Since the support for these properties was just added, it can't really affect much in userland. Some properties had been stored in the form which the XML requires them rather than as the user would enter them to Excel. So, for example, setting the Glow size to 10 points would have caused it to be stored internally as 127,000. This change will store the size internally as 10, obviously making the appropriate conversion when reading from or writing to XML. This makes unit tests much simpler, and I think this is also what a user would expect, especially considering the difficulties in keeping track of the trailing zeros.
* More Tests
Confirm value change between internal and xml.
* Still More Tests
Add a little more coverage, and use a neat trick suggested by @MarkBaker in the discussion of PR #2724 to greatly simplify MultiplierTest.
oleibman