A follow-on activity to PR #5061. That PR added scrollbars to the dropdown lists when samples were run in a browser. Earlier changes had broken up a number of categories into multiple entries because the dropdown lists were too long and wound up truncated. With the scrollbars, it makes sense to re-consolidate many of those lists, such as ComplexNumbers, which are all essentially the same test as each other. Some break-ups are retained (e.g. Basic/1/2/3/4/5) because they differ substantially from sample to sample; that's kind of an arbitrary decision, but it will have to do for now. I also renamed some of the members so that like members sort together when listing the directory (e.g. all pivot table samples now start with `pvt`). The sample code is mostly unchanged; only the directory and/or member names are changed.
The download samples were moved to their own new directory, and now represent a complete set of all the write formats that we permit. Studying their code, an improvement for `Helper\Downloader` became evident. It had been used merely to copy an existing file to be downloaded. However, by changing the first parameter of `download` to be either the name of the file directory (the existing usage) *or* a `Writer` object poised to issue `save`, you can use it to download your spreadsheet without having to worry about the headers which the browser requires. It then becomes generally useful beyond being used in samples:
```php
$writer = new WriterType($spreadsheet);
$downloader = new Downloader($writer, 'suggestedFileName.xlsx');
$downloader->download();
```
The samples have become unwieldy when running them from a browser. In particular, the drop-down lists are fixed size with no scrolling, and many of them are now just too large. I have moved all the Calculation samples up a level, and broken several categories (Basic, Chart, DateTime, Engineering, Financial, and Reader) into several pieces.
Convert-Online (now found in the Engineering category) had a number of different problems which are now resolved. It is the only member with any significant code change.
oleibman
Adrien Crivelli