Generalize auth/types.StdSignature (#4507)

New Signature interface available in the top level types package.
auth.StdSignature implements such interface. User defined auth
module can now define their own custom signature types.

Work carried out in the context of the following issues:
- #4488
- #4487

client/keys/import.go

@@ -3,8 +3,9 @@ package keys
 import (
 	"io/ioutil"
 
-	"github.com/cosmos/cosmos-sdk/client/input"
 	"github.com/spf13/cobra"
+
+	"github.com/cosmos/cosmos-sdk/client/input"
 )
 
 func importKeyCommand() *cobra.Command {

client/keys/list.go

@@ -1,8 +1,9 @@
 package keys
 
 import (
-	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/spf13/cobra"
+
+	"github.com/cosmos/cosmos-sdk/client/flags"
 )
 
 func listKeysCmd() *cobra.Command {

client/keys/mnemonic_test.go

@@ -5,9 +5,10 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/cosmos/cosmos-sdk/client/input"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/cosmos/cosmos-sdk/client/input"
 )
 
 func Test_RunMnemonicCmdNormal(t *testing.T) {

client/keys/update.go

@@ -3,8 +3,9 @@ package keys
 import (
 	"fmt"
 
-	"github.com/cosmos/cosmos-sdk/client/input"
 	"github.com/spf13/cobra"
+
+	"github.com/cosmos/cosmos-sdk/client/input"
 )
 
 func updateKeyCommand() *cobra.Command {

client/utils/utils_test.go

@@ -100,7 +100,7 @@ func TestReadStdTxFromFile(t *testing.T) {
 
 	// Build a test transaction
 	fee := authtypes.NewStdFee(50000, sdk.Coins{sdk.NewInt64Coin("atom", 150)})
-	stdTx := authtypes.NewStdTx([]sdk.Msg{}, fee, []authtypes.StdSignature{}, "foomemo")
+	stdTx := authtypes.NewStdTx([]sdk.Msg{}, fee, nil, "foomemo")
 
 	// Write it to the file
 	encodedTx, _ := cdc.MarshalJSON(stdTx)
@@ -143,8 +143,8 @@ func TestValidateCmd(t *testing.T) {
 	}{
 		{"misspelled command", []string{"comission"}, true},
 		{"no command provided", []string{}, false},
-		{"help flag", []string{"comission", "--help"}, false},
-		{"shorthand help flag", []string{"comission", "-h"}, false},
+		{"help flag", []string{"commission", "--help"}, false},
+		{"shorthand help flag", []string{"commission", "-h"}, false},
 	}
 
 	for _, tt := range tests {
@@ -158,7 +158,7 @@ func TestValidateCmd(t *testing.T) {
 
 func compareEncoders(t *testing.T, expected sdk.TxEncoder, actual sdk.TxEncoder) {
 	msgs := []sdk.Msg{sdk.NewTestMsg(addr)}
-	tx := authtypes.NewStdTx(msgs, authtypes.StdFee{}, []authtypes.StdSignature{}, "")
+	tx := authtypes.NewStdTx(msgs, authtypes.StdFee{}, []sdk.Signature{}, "")
 
 	defaultEncoderBytes, err := expected(tx)
 	require.NoError(t, err)