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Use an underscore '_' in front of the function name.

All the options are now stored in an object.

When using a literal IP address, the IP address is sent as SNI.
This may lead to a `close notify' from the server. Therefore we
decided to catch the OpenSSL error and suggest to use the --nosni
option.

Small improvements and fixes

* fix qtype usage
* send an independent first request with multistreams
* fix average time with multistreams
* add comments

See merge request bortzmeyer/homer!19

When using multistreams, requests are sent in parallel. curl keeps
track of different time values for each handle independently. This
means that we can retrieve the transfer duration for each handle
separatly.
It is then possible to calculate the average time taken by each
transfer independently. Even so this might be an interesting data to
compute, this does not reflect the benefits of using parallelism.
Therefore the average time taken by a request is calculate as the
total time elapsed to perform all the requests divided by the number
of transfers.

When using curl multi, we populate the multi with handles and then
call multi_perform which leads to curl establishing the multi
connection and sending tranfers once it is done. This looks
satfisfying enough if we don't look at the time values stored by curl
in each handles. In this case it appears that all the transfer time
are set to the time the curl multi was started meaning that all
transfers keep track of the connection time, this is normal for the
first transfer but unnecessary for all the following ones.

Therefore by sending a first transfer asking for the root NS, it
allows to open the connection without populating the resolver cache.
And thus keeps the curl timers more accurate.