Straightn http client generation

  - split CtdlFreeMessage into CtdlFreeMessageContents for places where CtdlMessage isn't kept as independent memory
  - move stuff about setting function pointers over to event_client.c
  - move stuff from evcurl_init over to evcurl_handle_start that depend on write by the client
  - call InitcURLIOStruct() way up than we did with evcurl_init ()