* 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.
* Charts Additional Support for Layout and DataSeriesValues
The dLbls tag in more or less the Xml equivalent of the Layout class. It is currently read and written only for the Chart as a whole. It can, however, also be applied to DataSeriesValues. Further it has properties which are currently ignored, namely label fill, border, and font colors. All of these omissions are handled by this PR. There are other properties which can be applied to the labels, but, for now, only the 3 colors are added.
DataSeriesValues can have effects (like glow). Since DSV now descends from Properties, these are already supported, but support needs to be added to the Reader and Writer to handle them. This PR adds the support.
* Add Unit Tests
Based on new samples.
* Minor Improvements
Slight increase to coverage.
oleibman