Although current two implementations(ledgerDriver, trezorDriver) of interface driver.Close do not actually return any error. Instead, they only return nil.
But since the declaration of Close function returns error, it is better to check the returned error in case in future some new implementation of Close function returns error and we may forget to modify the function which invokes Close function at that time.

This PR will will break existing UIs, since it changes all calls like ApproveSignTransaction to be on the form ui_approveSignTransaction.

This is to make it possible for the UI to reuse the json-rpc library from go-ethereum, which uses this convention.

Also, this PR removes some unused structs, after import/export were removed from the external api (so no longer needs internal methods for approval)

One more breaking change is introduced, removing passwords from the ApproveSignTxResponse and the likes. This makes the manual interface more like the rulebased interface, and integrates nicely with the credential storage. Thus, the way it worked before, it would be tempting for the UI to implement 'remember password' functionality. The way it is now, it will be easy instead to tell clef to store passwords and use them.

If a pw is not found in the credential store, the user is prompted to provide the password.

These tests never run as the build tag excluded them from the CI
execution. As a results the (dead) code got out of sync with other
parts of Swarm and now they would not even compile. => Removed.

resolves ethersphere/go-ethereum#1238

* swarm/network/stream: fixed timing issues

* swarm/network/stream: only count first iteration of subscriptions

* swarm/network/stream/: fix linter errors

all: clean up and properly abstract database accesses

p2p/protocols: Fix race condition in TestAccountingSimulation

consensus/clique: fix test copy paste error, test what's documented

* p2p/simulations: increased snapshot load timeout for debugging

* swarm/network/stream: less nodes for snapshot longrunning tests

* swarm/network: fixed longrunning tests

* swarm/network/stream: store kademlia in bucket

* swarm/network/stream: disabled healthy check in delivery tests

* swarm/network/stream: longer SyncUpdateDelay for longrunning tests

* swarm/network/stream: more debug output

* swarm/network/stream: reduced longrunning snapshot tests to 64 nodes

* swarm/network/stream: don't WaitTillHealthy in SyncerSimulation

* swarm/network/stream: cleanup for PR

build: add clef to alltools and deb

This reverts commit 460d206f.

* swarm/shed, swarm/storage/localstore: add LastPullSubscriptionChunk

* swarm/shed: fix comments

* swarm/shed: fix TestIncByteSlice test

* swarm/storage/localstore: fix TestDB_LastPullSubscriptionChunk

build/deb: fix PPA env var setting

build/deb: use custom cache for PPA builder

crypto/bn256/cloudflare: pull in upstream fix for Go 1.12 R18

core/types: fix receipt legacy decoding

* p2p/discover: remove unused function

* p2p/enode: use localItemKey for local sequence number

I added localItemKey for this purpose in #18963, but then
forgot to actually use it. This changes the database layout
yet again and requires bumping the version number.

* node: require LocalAppData variable

This avoids path inconsistencies on Windows XP.
Hat tip to @MicahZoltu for catching this so quickly.

* node: fix typo

* swarm/network: WIP consider all nodes for healthy iteration

* swarm/network/simulation: extend TestWaitTillHealthy to really check kads are healthy

* cmd/swarm/swarm-snapshot: fixed bugs in snapshot creation binary

* swarm/network/simulation: addressed PR comments

* swarm/network/simulation: defer sim.Clsoe()

* swarm/network/simulation: fixed wrong sim.Close()

* swarm/network/simulation: addressed PR comments

* cmd/swarm/swarm-snapshot: reducing default to 8 nodes, more to 4

* cmd/swarm/swarm-snapshot: extended timeout to 3 mins, or 256 nodes snapshot times out

* swarm/network/simulation: More PR comments

Upgrade to Go 1.12

* travis, build: switch to NDK 19b, fix gomobile builds

* travis, build: move NDK into its final bundle location

* travis: disable Android build on PRs once again