Added image file classes

Included in this release:

• ImageHelper: Added image file classes GIFFile, JPGFile, PNGFile and SVGFile.

Full Changelog

Minor enhancements.

Included in this release:

• ImageHelper: Added the method getImageFormat() to get the format of the current image.

Image formats

Included in this release:

• Formats: Added the utility collection class ImageFormats to provide a list of supported image formats.
• Formats: The GIF format offers the fileHasAnimation() method to check if a file contains an animation.
• Tests: Added some tests to guarantee backwards compatibility with the previous version.

Initial release

Included in this release:

• Split off as a separate library from mistralys/application-utils.