• Fixes #201: do not count repeated headers with same name against the field
  count limit. The are merged internally, as if sent in a single HTTP/1 line.
• Refrain from detecting (intermediate) responses, when the connection has
  already been aborted or non-flush meta buckets are encountered.
• Changed terminology to master/secondary connections in the source.
• Test against the installed version of the module. This allows test cases
  to work with other versions.