Make commands join args with spaces

This patch ensures the following commands join their arguments with
spaces to make it easier to interact with:

- cf
- mkdir
- cd
- attach
- detach
- ct
- copy
- move
- save

commands/compose/attach.go

@@ -3,6 +3,7 @@ package compose
 import (
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
 	"git.sr.ht/~sircmpwn/aerc/commands"
@@ -22,20 +23,16 @@ func (Attach) Aliases() []string {
 }
 
 func (Attach) Complete(aerc *widgets.Aerc, args []string) []string {
-	path := ""
-	if len(args) >= 1 {
-		path = args[0]
-	}
-
+	path := strings.Join(args, " ")
 	return commands.CompletePath(path)
 }
 
 func (Attach) Execute(aerc *widgets.Aerc, args []string) error {
-	if len(args) != 2 {
+	if len(args) == 1 {
 		return fmt.Errorf("Usage: :attach <path>")
 	}
 
-	path := args[1]
+	path := strings.Join(args[1:], " ")
 
 	path, err := homedir.Expand(path)
 	if err != nil {

commands/compose/detach.go

@@ -2,6 +2,7 @@ package compose
 
 import (
 	"fmt"
+	"strings"
 	"time"
 
 	"git.sr.ht/~sircmpwn/aerc/widgets"
@@ -20,7 +21,6 @@ func (Detach) Aliases() []string {
 
 func (Detach) Complete(aerc *widgets.Aerc, args []string) []string {
 	composer, _ := aerc.SelectedTab().(*widgets.Composer)
-
 	return composer.GetAttachments()
 }
 
@@ -28,12 +28,8 @@ func (Detach) Execute(aerc *widgets.Aerc, args []string) error {
 	var path string
 	composer, _ := aerc.SelectedTab().(*widgets.Composer)
 
-	if len(args) > 2 {
-		return fmt.Errorf("Usage: :detach [path]")
-	}
-
-	if len(args) == 2 {
-		path = args[1]
+	if len(args) > 1 {
+		path = strings.Join(args[1:], " ")
 	} else {
 		// if no attachment is specified, delete the first in the list
 		atts := composer.GetAttachments()