Add X13 WebP module for image conversion to next-generation formats

- Implemented the X13Webp class with core functionalities for converting images to WebP format.
- Added support for different PHP versions and defined constants for versioning.
- Included translation strings for various user interface elements and messages.
- Created XML file for module versioning.

modules/x13webp/vendor/rosell-dk/webp-convert/docs/development.md

@@ -0,0 +1,79 @@
+# Development
+
+## Setting up the environment.
+
+First, clone the repository:
+```
+cd whatever/folder/you/want
+git clone https://github.com/rosell-dk/webp-convert.git
+```
+
+Then install the dev tools with composer:
+
+```
+composer install
+```
+
+If you don't have composer yet:
+- Get it ([download phar](https://getcomposer.org/composer.phar) and move it to /usr/local/bin/composer)
+- PS: PHPUnit requires php-xml, php-mbstring and php-curl. To install: `sudo apt install php-xml php-mbstring curl php-curl`
+
+
+## Unit Testing
+To run all the unit tests do this:
+```
+composer test
+```
+This also runs tests on the builds.
+
+
+Individual test files can be executed like this:
+```
+composer phpunit tests/Convert/Converters/WPCTest
+composer phpunit tests/Serve/ServeConvertedTest
+```
+
+
+## Coding styles
+WebPConvert complies with the [PSR-2](https://www.php-fig.org/psr/psr-2/) coding standard.
+
+To validate coding style of all files, do this:
+```
+composer phpcs src
+```
+
+To automatically fix the coding style of all files, using [PHP_CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer), do this:
+```
+composer phpcbf src
+```
+
+Or, alternatively, you can fix with the use the [PHP-CS-FIXER](https://github.com/FriendsOfPHP/PHP-CS-Fixer) library instead:
+```
+composer cs-fix
+```
+
+## Running all tests in one command
+The following script runs the unit tests, checks the coding styles, validates `composer.json` and runs the builds.
+Run this before pushing anything to github. "ci" btw stands for *continuous integration*.
+```
+composer ci
+```
+
+## Generating api docs
+Install phpdox and run it in the project root:
+```
+phpdox
+```
+
+## Committing
+Before committing, first make sure to:
+- run `composer ci`
+
+## Releasing
+Before releasing:
+- Update the version number in `Converters/AbstractConverter.php` (search for "WebP Convert")
+- Make sure that ci build is successful
+
+When releasing:
+- update the [webp-convert-concat](https://github.com/rosell-dk/webp-convert-concat) library
+- consider updating the require in the composer file in libraries that uses webp-convert (ie `webp-convert-cloud-service` and `webp-express`)