Merge pull request Exercise#52 from heahprod/configure-definition

[3.0] Fixed warming up custom configs and added support for custom config definition

Merge pull request Exercise#71 from heahprod/pump-readme

Added badges in README

Merge pull request Exercise#61 from mpiot/fix-symfony-deprecation

Implement static function getExtendedTypes(): iterable in place of getExtendedType

Merge pull request Exercise#62 from mpiot/fix-tree-root-deprecations

Fix Symfony Tree root deprecation (fix Exercise#59)

Merge pull request Exercise#53 from sweoggy/patch-1

Fixed exception when using TextType without purify options

Merge pull request Exercise#55 from alister/patch-1

kernel.cache_warmer & fixing service definition

Merge pull request Exercise#55 from alister/patch-1

kernel.cache_warmer & fixing service definition

Added missing dependencies

Added missing dependencies

Merge pull request Exercise#47 from stof/symfony_4

Add support for Symfony 4