Migrate to btcd/btcutils submodule

[3nprob]

As per btcsuite/btcd#1785, btcutil needs to migrate as well in order to afford upgrading the btcd dependency. Attempting to use current btcd@master:

$ GO111MODULE=on go install -v . ./cmd/...
github.com/btcsuite/btcwallet/internal/legacy/keystore
github.com/btcsuite/btcwallet/wallet/txrules
github.com/lightninglabs/neutrino
# github.com/btcsuite/btcwallet/wallet/txrules
wallet/txrules/rules.go:30:23: cannot use relayFeePerKb (type "github.com/btcsuite/btcutil".Amount) as type "github.com/btcsuite/btcd/btcutil".Amount in argument to mempool.IsDust
# github.com/btcsuite/btcwallet/internal/legacy/keystore
internal/legacy/keystore/keystore.go:2795:3: cannot use addresses (type []"github.com/btcsuite/btcd/btcutil".Address) as type []"github.com/btcsuite/btcutil".Address in field value
internal/legacy/keystore/keystore.go:2877:15: cannot use addresses (type []"github.com/btcsuite/btcd/btcutil".Address) as type []"github.com/btcsuite/btcutil".Address in assignment
# github.com/lightninglabs/neutrino
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/blockmanager.go:2718:35: cannot use stubBlock (type *"github.com/btcsuite/btcutil".Block) as type *"github.com/btcsuite/btcd/btcutil".Block in argument to blockchain.CheckProofOfWork
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/query.go:988:42: cannot use block (type *"github.com/btcsuite/btcutil".Block) as type *"github.com/btcsuite/btcd/btcutil".Block in argument to blockchain.CheckBlockSanity
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/rescan.go:931:53: cannot use relevantTxs (type []*"github.com/btcsuite/btcutil".Tx) as type []*"github.com/btcsuite/btcd/btcutil".Tx in argument to ro.ntfn.OnFilteredBlockConnected
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/rescan.go:988:26: cannot use tx (type *"github.com/btcsuite/btcutil".Tx) as type *"github.com/btcsuite/btcd/btcutil".Tx in argument to ro.ntfn.OnRedeemingTx
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/rescan.go:1004:21: cannot use tx (type *"github.com/btcsuite/btcutil".Tx) as type *"github.com/btcsuite/btcd/btcutil".Tx in argument to ro.ntfn.OnRecvTx
../../../../pkg/mod/github.com/lightninglabs/neutrino@v0.12.1/rescan.go:1048:44: cannot use relevantTxs (type []*"github.com/btcsuite/btcutil".Tx) as type []*"github.com/btcsuite/btcd/btcutil".Tx in argument to ro.ntfn.OnFilteredBlockConnected

[chappjc]

Related: #782
With the last tagged release, you cannot just go get or even add a require for btcwallet because it currently relies on replaces.

[3nprob]

As seen above, there are also several references in Neutrino, which is addressed here: lightninglabs/neutrino#242

[chappjc]

Ahhh, dang I did not even see that btcutil was moved into the btcd repo as a submodule in btcsuite/btcd#1785. About a month ago now. I'm just going to close the PR I linked, but note that you can get wallet to build if you set your requires to specific revisions in that way, but I get your issue now that code changes are needed to use the new btcutil import path. 👍

[3nprob]

@chappjc Ah , I looked at your PR now - I was actually just about to do a similar one here, to address this issue. Would you say that what you addressed in your PR and 825e09b still is relevant to put on top of a btcd dependency upgrade here?

[chappjc]

The wtxmgr thing is still an issue, especially for a tagged release, and all the replaces were just hiding the issues from devs who either work directly out of a git workspace or had their own requires patching it up. Tagged releases should really have replaces removed. It would still be nice if 0.13 were properly re-released with a 0.13.1 patch, but with these btcutil changes at hand now, it's probably a moot point now.

I say you should go ahead and fix things up with btcutil. If the maintainers are interested in a usable 0.13.x with the previous btcutil module, I'm happy to update my PR.

With these big btcutil changes, I'm curious if the intent is to bump to 0.14 or just patch 0.13.

[Roasbeef]

With these big btcutil changes, I'm curious if the intent is to bump to 0.14

We'll likely just do a big ump everywhere.

[Roasbeef]

Has been done in master.