This change is per discussion at http://forum.bitcoin.org/index.php?topic=8153.0;
Added ability to estimate the transaction fee for a given transfer amount. Use case concerns transferring BTC out of an "account", and being able to determine if the account has enough BTC to cover transfer + fees.
*Accidentally closed previous pull request trying to rebase to one commit.
Seems OK, but I'd have to glance at CreateTransaction() callee's, to make 100% certain there are no side effects.
The only other question I have is whether or not there is a driving need? (yes, I did review the thread)
I prefer an option to create transactions without committing them, allowing to inspect them, and then decide to commit+send or to abort.
I agree w. sipa, I like the create...inspect...commit paradigm better.
Im just not a huge fan of this as its an estimate and could very well be far off the estimate. I agree with gavin and sipa here and had done it in one of the commits in #289
consensus seems to be against