Rather than having to keep the usage in sync with the supported commands,
simply include the usage as a field in the command handlers map and
dynamically generate the usage from there.
This commit modifies the command handler in btcctl to check the existence
of a display handler before issues an RPC command. This prevents a round
trip to the server if there is no display handler.
Also, fix a couple of comments while here.
This commit significantly reworks btcctl to use a map based approach to
command handling. This reduces the number of lines of code needed,
simplifies adding new commands, improves the error handling, and removes
several cases where unexpected data was not handled properly (it could
panic).
This commit also adds the ability to specify the optional parameter on
getrawtransaction.
Discussed with dhill@.
This change paves the way for running btcwallet on the same system without
having to change any settings. The well-known ports used by the
reference implementation (8332 mainnet, 18332 testnet) will be exposed by
the separate wallet process, which will in turn forward unknown requests
to btcd via websockets (on 8334/18334). This allows the wallet process to
ultimately provide a unified interface that exposes the same RPC-JSON API
as the reference implementation will maintaining wallet and chain
separation.
