gometalinter -> golangci-lint migration (#3933)

{,scripts/}Makefile:
- Remove gometalinter, install golangci-lint.
- Remove distinction between tools and devtools.
  Just tools is enough.
- test_lint -> lint
  Migrating away from underscore separated names.
- Remove unnecessary targets.
- Drop tendermint/lint. Incompatbile with golangci-lint
  and no longer necessary anyway.
- Fix misleading message in go-mod-cache.
- New ci-target to avoid download tools twice.
- Run tests with -mod=readonly.

Port tools/gometalinter.json to .golangci.yml
Update CircleCI config accordingly.

Closes: #3896

client/lcd/certificates.go

@@ -145,7 +145,9 @@ func fingerprintForCertificate(certBytes []byte) (string, error) {
 		return "", err
 	}
 	h := sha256.New()
-	h.Write(cert.Raw)
+	if _, err := h.Write(cert.Raw); err != nil {
+		return "", err
+	}
 	fingerprintBytes := h.Sum(nil)
 	var buf bytes.Buffer
 	for i, b := range fingerprintBytes {

client/lcd/test_helpers.go

@@ -227,7 +227,7 @@ func InitializeTestLCD(t *testing.T, nValidators int, initAddrs []sdk.AccAddress
 	genDoc, err := tmtypes.GenesisDocFromFile(genesisFile)
 	require.Nil(t, err)
 	genDoc.Validators = nil
-	genDoc.SaveAs(genesisFile)
+	require.NoError(t, genDoc.SaveAs(genesisFile))
 	genTxs := []json.RawMessage{}
 
 	// append any additional (non-proposing) validators
@@ -337,7 +337,7 @@ func InitializeTestLCD(t *testing.T, nValidators int, initAddrs []sdk.AccAddress
 
 	cleanup = func() {
 		logger.Debug("cleaning up LCD initialization")
-		node.Stop()
+		node.Stop() //nolint:errcheck
 		node.Wait()
 		lcd.Close()
 	}
@@ -394,7 +394,7 @@ func startLCD(logger log.Logger, listenAddr string, cdc *codec.Codec, t *testing
 	if err != nil {
 		return nil, err
 	}
-	go tmrpc.StartHTTPServer(listener, rs.Mux, logger)
+	go tmrpc.StartHTTPServer(listener, rs.Mux, logger) //nolint:errcheck
 	return listener, nil
 }
 
@@ -559,7 +559,7 @@ func getKeys(t *testing.T, port string) []keys.KeyOutput {
 
 // POST /keys Create a new account locally
 func doKeysPost(t *testing.T, port, name, password, mnemonic string, account int, index int) keys.KeyOutput {
-	pk := clientkeys.AddNewKey{name, password, mnemonic, account, index}
+	pk := clientkeys.NewAddNewKey(name, password, mnemonic, account, index)
 	req, err := cdc.MarshalJSON(pk)
 	require.NoError(t, err)
 
@@ -585,7 +585,7 @@ func getKeysSeed(t *testing.T, port string) string {
 
 // POST /keys/{name}/recove Recover a account from a seed
 func doRecoverKey(t *testing.T, port, recoverName, recoverPassword, mnemonic string, account uint32, index uint32) {
-	pk := clientkeys.RecoverKey{recoverPassword, mnemonic, int(account), int(index)}
+	pk := clientkeys.NewRecoverKey(recoverPassword, mnemonic, int(account), int(index))
 	req, err := cdc.MarshalJSON(pk)
 	require.NoError(t, err)
 
@@ -613,7 +613,7 @@ func getKey(t *testing.T, port, name string) keys.KeyOutput {
 
 // PUT /keys/{name} Update the password for this account in the KMS
 func updateKey(t *testing.T, port, name, oldPassword, newPassword string, fail bool) {
-	kr := clientkeys.UpdateKeyReq{oldPassword, newPassword}
+	kr := clientkeys.NewUpdateKeyReq(oldPassword, newPassword)
 	req, err := cdc.MarshalJSON(kr)
 	require.NoError(t, err)
 	keyEndpoint := fmt.Sprintf("/keys/%s", name)
@@ -627,7 +627,7 @@ func updateKey(t *testing.T, port, name, oldPassword, newPassword string, fail b
 
 // DELETE /keys/{name} Remove an account
 func deleteKey(t *testing.T, port, name, password string) {
-	dk := clientkeys.DeleteKeyReq{password}
+	dk := clientkeys.NewDeleteKeyReq(password)
 	req, err := cdc.MarshalJSON(dk)
 	require.NoError(t, err)
 	keyEndpoint := fmt.Sprintf("/keys/%s", name)