cli: extend NewCommand() to NewCommands()

So that each module could now return an array of commands. It's gonna be used
in the future to extend them.

cli/main.go

@@ -17,12 +17,10 @@ func main() {
 	ctl.Version = config.Version
 	ctl.Usage = "Official Go client for Neo"
 
-	ctl.Commands = []cli.Command{
+	ctl.Commands = append(ctl.Commands, server.NewCommands()...)
-		server.NewCommand(),
+	ctl.Commands = append(ctl.Commands, smartcontract.NewCommands()...)
-		smartcontract.NewCommand(),
+	ctl.Commands = append(ctl.Commands, wallet.NewCommands()...)
-		wallet.NewCommand(),
+	ctl.Commands = append(ctl.Commands, vm.NewCommands()...)
-		vm.NewCommand(),
-	}
 
 	if err := ctl.Run(os.Args); err != nil {
 		panic(err)

cli/server/server.go

@@ -16,9 +16,9 @@ import (
 	"github.com/urfave/cli"
 )
 
-// NewCommand creates a new Node command.
+// NewCommands returns 'node' command.
-func NewCommand() cli.Command {
+func NewCommands() []cli.Command {
-	return cli.Command{
+	return []cli.Command{{
 		Name:   "node",
 		Usage:  "start a NEO node",
 		Action: startServer,
@@ -29,7 +29,7 @@ func NewCommand() cli.Command {
 			cli.BoolFlag{Name: "testnet, t"},
 			cli.BoolFlag{Name: "debug, d"},
 		},
-	}
+	}}
 }
 
 func newGraceContext() context.Context {

cli/smartcontract/smart_contract.go

@@ -35,9 +35,9 @@ func Main(op string, args []interface{}) {
 }`
 )
 
-// NewCommand returns a new contract command.
+// NewCommands returns 'contract' command.
-func NewCommand() cli.Command {
+func NewCommands() []cli.Command {
-	return cli.Command{
+	return []cli.Command{{
 		Name:  "contract",
 		Usage: "compile - debug - deploy smart contracts",
 		Subcommands: []cli.Command{
@@ -98,7 +98,7 @@ func NewCommand() cli.Command {
 				},
 			},
 		},
-	}
+	}}
 }
 
 // initSmartContract initializes a given directory with some boiler plate code.

cli/vm/vm.go

@@ -9,9 +9,9 @@ import (
 	"github.com/urfave/cli"
 )
 
-// NewCommand creates a new VM command.
+// NewCommands returns 'vm' command.
-func NewCommand() cli.Command {
+func NewCommands() []cli.Command {
-	return cli.Command{
+	return []cli.Command{{
 		Name:   "vm",
 		Usage:  "start the virtual machine",
 		Action: startVMPrompt,
@@ -31,7 +31,7 @@ func NewCommand() cli.Command {
 				},
 			},
 		},
-	}
+	}}
 }
 
 func startVMPrompt(ctx *cli.Context) error {

cli/wallet/wallet.go

@@ -16,9 +16,9 @@ var (
 	errPhraseMismatch = errors.New("the entered pass-phrases do not match. Maybe you have misspelled them")
 )
 
-// NewCommand creates a new Wallet command.
+// NewCommands returns 'wallet' command.
-func NewCommand() cli.Command {
+func NewCommands() []cli.Command {
-	return cli.Command{
+	return []cli.Command{{
 		Name:  "wallet",
 		Usage: "create, open and manage a NEO wallet",
 		Subcommands: []cli.Command{
@@ -49,7 +49,7 @@ func NewCommand() cli.Command {
 				},
 			},
 		},
-	}
+	}}
 }
 
 func openWallet(ctx *cli.Context) error {