Merge branch '3.4'

* 3.4:
  [Yaml] Recommend using quotes instead of PARSE_KEYS_AS_STRINGS
  [DependencyInjection] Deprecate autowiring service auto-registration
  Removed useless argument $definition
  [DI] Generate shorter method names for class-based ids
  Fix comment
  [Config] Fix checking class existence freshness
  bumped Symfony version to 3.3.7
  updated VERSION for 3.3.6
  updated CHANGELOG for 3.3.6
  Autoconfigure instances of ArgumentValueResolverInterface
  Deprecate Filesystem/LockHandler
  improve sql explain table display
  Bump minimal PHP version to ^5.5.9|>=7.0.8

Author: nicolas-grekas