Remove NOOPs from OTServerConnection.cpp

Remnants from the SSL mode
Merge pull request #393 from OttoAllmendinger/pr-transport-fixes

Remove NOOPs from OTServerConnection.cpp
Choose minimal available number for transactions

It is only cosmetic fix. Get new numbers for transaction in increasing order.
Merge pull request #390 from mhamrle/nums

Choose minimal available number for transactions
cppcheck: upgrade to 1.67
Merge pull request #391 from toxeus/upgradeCppCheck

cppcheck: upgrade to 1.67
OTCheque: rename class to Cheque
OTCheque: rename files to Cheque.{h,c}pp
Merge pull request #387 from toxeus/develop

OTCheque: rename to Cheque
UserCmdGetBoxReceipt: remove unused parameter
UserCmdGetBoxReceipt: remove commented out condition
Merge pull request #397 from toxeus/develop

UserCmdGetBoxReceipt: remove confusions
Use SendMessage() call

OT still has some remnants of a SSL connection system that was removed in favor
of ZeroMQ. The OTServerConnection class does a lot of stuff that may have made
sense earlier but can be removed and simplified now.

This is the first step of a larger cleanup.

The old code had this repeated pattern

m_pClient->SetFocusToServerAndNym(*pServer, *pNym, m_pTransportCallback);
m_pClient->ProcessMessageOut(theMessage);
return m_pClient->CalcReturnVal(lRequestNumber);

and a variant that does not have last call to CalcReturnVal()

I replaced these two variants two atomic methods

* SendMessage(OTServerContract*, OTPseudonym*, OTMessage&, lRequestNumber)
* SendMessage(OTServerContract*, OTPseudonym*, OTmessage&)

The other place where SetFocusToServerAndNym is called now is in opentxs-script
which I will do separately.
Merge pull request #395 from OttoAllmendinger/pr-otapi-sendmessage

Use SendMessage() call
Fixed mixup between empty() and clear() so memory is realesed correctly
OTMessage: rename class to Message
OTMessage: rename files to Message.{h,c}pp
Merge pull request #398 from BugFreeSoftware/fix_cmd

Fixed mixup between empty() and clear() so memory is realesed correctly
Merge pull request #399 from toxeus/renameOTMessage

OTMessage: rename to Message
Some small comment cleanups