Update chain state with best block.

Rather than updating the new chain state with the hash and height of the
block that was just processed, query the database for the best block.
This is needed because the block that was just processed might be a side
chain block or have caused a reorg.
Preallocate the tx serialization buffer.
Benchmarking shows this is slightly faster due to avoiding the extra
garbage collection in addition to less peak memory usage.

ok @davecgh
Don't fail RPC server create due to single iface.

Rather than returning an error when creating the RPC server an it can't
listen on any of the specified interfaces, only error when it can't listen
on all of the specified interfaces.
Optimize rescan.

This change adds rescan fast paths for all current implementations of
the btcutil.Address interface.  Rather than encoding a payment address
string from a txout script, the minimum number of bytes (which depends
on the address type) are copied into a stack array and used as a
lookup key to a map exclusive for that address type.  This performs
better than the previous implementation due to avoiding the base58
encoding and generating less garbage (so each GC cycle completes
faster).

If the address type switch falls into the default (unhandled) case,
the encoded payment address is used as a fallback.  This keeps the
intended rescan behavior even when new implementations of
btcutil.Address are added without a rescan fast path.

Benchmarks indicate that when a fast path is followed, for 20 byte
RIPEMD-160 hashes (such as P2PKH and P2SH), skipping the payment
address encoding (and thus bypassing the base58 encoding code) can
result in map lookups up to 60x faster.
Bootstrap unspents with rescan request's outpoints.
Prevent blocking on RPC server messages after shutdown.

This change adds select statements to each channel write that may
occur from a non-RPCS goroutine to unblock once the server has begun
shutting down.  This prevents issues in clean shutdown where non-RPCS
goroutines may block indefinitely on message sends to the RPC server.
Add new logging subsystem for mining related ops.

This commit adds a new logging subsystem named MINR which is used for
logging mining releated operations.
Add options to control block creation settings.

This commit adds three new options which are intended to to be used by the
upcoming mining-related block template creation code.
Add infrastructure for creating a block template.

This commit adds a new function named NewBlockTemplate along with
supporting infrastructure which is part of the core functionality needed
to support mining.

In particular the function creates a new block template which contains a
fully populated block with a zero nonce that is ready to be solved as well
as additional information regarding the fees and number of signature
operations for each transaction included in the block.  The specific
transaction selection logic mirrors the reference implementation.

Various cleanup, optimizations, and comment suggestions provided by
@owainga.  Also contains some naming suggestions and comment fixes from
@flammit.
Switch RPC server to use fastsha256 package.
Bugfix for issue #101.
Update handleGetBlock to not use deprecated func.

Rather than using the deprecated TxShas function on a btcutil.Block,
convert handleGetBlock to use the newer preferred method of ranging over
the Transactions to obtain the cached hash of each transaction.

This is a little more efficient since it can avoid creating and caching an
extra slice to keep the hashes in addition to having the hash cached with
each transaction.
add importwallet to btcctl
Implement a rebroadcast handler.

This commit implements a rebroadcast handler which deals with
rebroadcasting inventory at a random time interval between 0 and 30
minutes.  It then uses the new rebroadcast logic to ensure transactions
which were submitted via the sendrawtransaction RPC are rebroadcast until
they make it into a block.

Closes #99.
Don't discuss internals in exported func comments.

This commit cleans up and moves a couple of comments in the recent pull
request which implements a rebroadcast handler (#114) in order to avoid
discussing internal state in the exported function comment.

How a function actually accomplishes the stated functionality is not
something that a caller is concerned with.  The details about the internal
state are better handled with comments inside the function body.
Kill duff newline.
simplify comment and fit into 80 cols.
Correct type capitalisation in comment.
comments - shorten, simplify and make 80cols.
Update websocket clients with rescan progress.

This change periodically (about every 10 seconds) notifies the
connected websocket client of the height of the last processed block
as part of the rescan.  This enables clients to listen for the
notification and keep track of how much progress a rescan has made
even without any results being found.  If the websocket connection is
lost during the rescan, on reconnect, clients may safely start over at
the last notified height.