v2.0.20

• add descriptionHtml() method to Ebook::class, which can contains description with html tags if it is available, html is sanitized, original description is still available via description() method with plain text
• add getBasename() method to Ebook::class, which returns basename of ebook file, getFilename() now return real filename of ebook file
• add isValid(string $path) static method to Ebook::class, which checks if ebook file is valid, thanks to @SergioMendolia: #38
• fix <dc:creator> empty tag in opf file, thanks to @SergioMendolia: #39
• Bugfixes