add "wrench version" command

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

main.go

@@ -24,6 +24,7 @@ The commands are:
 	runners    (remote) list registered runners
 	secret     (remote) manage secrets
 	git        manage local git repositories
+	version    print the wrench version
 
 Use "wrench <command> -h" for more information about a command.
 `

version.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/hexops/cmder"
+	"github.com/hexops/wrench/internal/errors"
+	"github.com/hexops/wrench/internal/wrench"
+)
+
+func init() {
+	usage := `wrench version: print the wrench version
+
+Usage:
+
+	wrench version
+
+`
+
+	// Parse flags for our subcommand.
+	flagSet := flag.NewFlagSet("version", flag.ExitOnError)
+
+	// Handles calls to our subcommand.
+	handler := func(args []string) error {
+		_ = flagSet.Parse(args)
+		if len(args) != 0 {
+			return &cmder.UsageError{Err: errors.New("expected no arguments")}
+		}
+
+		fmt.Println("wrench version", wrench.Version, "built using", wrench.GoVersion)
+
+		return nil
+	}
+
+	// Register the command.
+	commands = append(commands, &cmder.Command{
+		FlagSet: flagSet,
+		Aliases: []string{},
+		Handler: handler,
+		UsageFunc: func() {
+			fmt.Fprintf(flag.CommandLine.Output(), "Usage of 'wrench %s':\n", flagSet.Name())
+			flagSet.PrintDefaults()
+			fmt.Printf("%s", usage)
+		},
+	})
+}