…ansport; reject addresses starting with a dash

* 5.4:
  [Mailer] Add end-of-options separator before recipients in SendmailTransport; reject addresses starting with a dash
  [Yaml] Harden the Parser::cleanup() regexes against catastrophic backtracking
  [Yaml] Bound collection-alias resolution in the parser
  [Yaml] Bound recursion depth in the parser
  [MonologBridge] Bind server:log to localhost by default
  [Cache] Validate the prefix given to AbstractAdapter::clear()
  [Mime] Reject email addresses containing line breaks in Address
  [Security] Anchor emailAddress regex to RDN boundary in X509Authenticator
  [DomCrawler] Fix XXE in addXmlContent() by not enabling `validateOnParse`
  [Routing] Fix regex alternation anchoring in UrlGenerator requirement validation