move methods to new files to keep things a bit organized.
add rebroadcast of unconfirmed txs after sync
mutex on OKtxid map
deal with doublespends next
when we get inv messages, txs are easy but blocks are a little tricky
block heigh synchronization is done via os' file system
signing is a bit inelegant (searches through inputs for pkscript matches)
but fast enough in practice