* Font and Effects Support for Chart Data Labels and Axis
Addresses some remaining issues with 32readwriteLineChart5 (see issue #1797). Font size is covered. So are effects, although the results are a bit odd. For the new spreadsheet 32readwriteLineChart6, the Axis labels have a yellow-ish glow, but reading and writing the spreadsheet in PhpSpreadsheet gives them a purple-ish glow. Nevertheless, the new test shows that the output file uses schemeClr accent4, as does the input file. So the effect is handled correctly, but it seems there is likely to be a difference between theme colors (Writer/Xlsx/Theme appears to write hard-coded color schemes, and, in any case, Reader/Xlsx does not appear to handle schemeClr). Fixing that will be a great deal more difficult, with a large chance of regression, and will need to happen in a separate PR (one that I am not currently investigating, but I will open a new issue). Effects using srgbClr (and probably sysclr) should be okay.
* Better Theme Support
When reading Xlsx, the theme colors will now also be used for writing. This means that a file can be loaded and saved and its chart colors will now be preserved. If the spreadsheet is created new, Excel 2007-2010 colors are used. The writer is currently hard-coded to use them, so this avoids making this a breaking change. The theme colors can be explicitly changed if desired, and Excel 2013+ colors can be introduced very easily.
```php
$spreadsheet->getTheme()
->setThemeColorName(Theme::COLOR_SCHEME_2013_PLUS_NAME);
```
Likewise, if the old behavior of changing to the 2007-2010 scheme rather than using the input values is desired, that is easy to achieve after the load has taken place.
```php
$spreadsheet->getTheme()
->setThemeColorName(Theme::COLOR_SCHEME_2007_2010_NAME);
```
The new Theme class introduced by this change can easily be extended to include Fonts and Effects. Unlike Colors, I am unsure what the practical effects of changing those to, say, the 2013+ defaults would be.
* Scrutinizer
Use an alias in a use statement.
* Update Change Log
Due to potential behavior change.
Fix#3453. User sets a valid formula (e.g. `=SUM(Sheet2!B1:Sheet2!B3)`), and then does something to invalidate the formula (e.g. delete Sheet2). Excel changes the formula to `SUM(#REF!:#REF!)` when the spreadsheet is saved; apparently someone thought this was a good idea. But PhpSpreadsheet (a) used to throw an Exception when it evaluated the formula, and (b) now gives a result of `0` when evaluating the formula. Neither is ideal. It would be better to propagate the `#REF!` error.
It is likely that more tests are needed, which is why I will keep this in draft status for a bit.
* Support Border for Charts
All chart linestyles will be supported for Chart Border. Also add fill color for Chart. Also 'nofill' for Axis (allows suppressing of vertical axis line). These are demonstrated in sample 32_readwriteChartLine5, and a new unit test member is added. This addresses some vague problems added to issue #1797 over 8 months after it was closed; there is still at least one problem, much more complicated than the 2 being addressed in this PR.
* Handle Legend Borders in Same Way as Chart Borders
Consistency is good, and the implementation of Chart Borders offers more possibilities than the implementation of Legend Borders had. Since Legend Borders hasn't made it to a release yet, there is no need for deprecations.
* Xlsx Writer Honor Alignment in Default Font
Fix#3443. A mysterious implementation by Excel. The style tags have an attribute applyAlignment, which nominally says whether or not the style should use its own Alignment. Except ... Excel ignores that attribute and uses the alignment tag if it is supplied ... and, another mystery, uses not the default style for the spreadsheet if not supplied, but rather uses the default alignment style for all spreadsheets even if the spreadsheet's default style uses a non-default alignment. I am changing Xlsx Writer to generate alignment tag unless the alignment matches both the default alignment for the spreadsheet and the default alignment for all spreadsheets (which I expect to happen most of the time).
* Improve Performance
Also don't change horizontal/vertical on Xlsx Read if they aren't explicitly set.
* Specify data type in html tags using attributes #3444
* Set data types using attributes in flushCell function and add some unit tests
* Check TYPE_INLINE in flushCell and some changes in test cases
Mark Baker
oleibman
Esteban Gehring
anhoder
Pouria Seyfi