Fixed propagation of eCAP transaction meta-information to core Squid

Fixed propagation of eCAP transaction meta-information to core Squid
by synchronizing the history of the virgin and eCAP-adapted/cloned request.

If the request history is created after the request got cloned, the cloned
request will have no history unless we explicitly import the newly created
history. Hopefully, it is not possible for the cloned request to get its own,
diverging history before the import (we check and throw if that happens).

This is one more example why a MasterTransaction class (with history) needs
to be extracted and separated from the HttpRequest class.