Merge pull request #472 from benma/renamings

Rename getTransactionNumber functions to match the getTransactionNumbers...
fix: rename OTLog to Log
Merge pull request #474 from toxeus/fixOTLog

fix: rename OTLog to Log
Clean up usage of issueNextTransactionNum.

Problem: issueNextTransactionNum took a nym and bSaveTheNumber as
parameters. The nym is used only if bSaveTheNumber is true. This case is
a legacy case from the time where the notary assigned tx nums to nyms
without requiring them to sign for them. For the normal case, no nym is
required, but one is passed on every call anyway.
Two instances of an invocation with bSaveTheNumber=true remain, which
need a closer look. This commit cleans up the signature and invocations
of that function, and introduces a new function
`issueNextTransactionNumberToNym` to handle the two odd cases.
In UserCmdGetTransactionNumbers, delete code that removes tx nums from
the nym.

Reason: they were never added in the first place.
getTransactionNumbersResponse: allocate a separate transaction
number for the receipt instead of reusing one of the numbers signed out
to the client.