Big refactoring: switched to full Event system

• No more processing logic in InterventionRequest
• No more response creation in InterventionRequest
• All Images processors are dependent on one ChainProcessor instance
• Cache and non-cached logic are now Request event subscribers
• Fixed WEBP processing for non pass-through caches
• Refactored cache path resolving (fewer folder depth)
• Deprecated AbstractProcessor, just implement Processor interface
• Only use allowed query params to generate a cache hash
• Refactored response header params names
• More type-hinting
• Only instanciate Intervention Image when needed, when we actually need to process image

Symfony 4.4 support

• FQCN Event names

Major changes

• Pass-through cache enables generated images to be directly served by Apache/Nginx by-passing your PHP process. This can reduce dramatically time-to-first-byte after first image request.
  https://github.com/ambroisemaupate/intervention-request#use-pass-through-cache
• WebP support, only if your PHP-GD extension is compiled with webp support. Add .webp extension after your image filename to convert it to webp format and save up precious bytes.
  https://github.com/ambroisemaupate/intervention-request#convert-to-webp
  https://caniuse.com/#feat=webp
• Added new listener for tinify.io image optimizing service.
  https://github.com/ambroisemaupate/intervention-request#tinyjpgcom

• Add compatibility with Symfony 3.2 and 2.8 LTS

Changelog

• Using Symfony 2.7 LTS libs
• Added optional file checksum to see if file has been changed with same name
• Added 404 error response when requested image does not exist
• Added 400 error response when requested image is not specified
• Added configurable default quality