Remove github.com/pkg/errors and replace with std library version

This is possible now that we no longer support go1.12 and brings
rclone into line with standard practices in the Go world.

This also removes errors.New and errors.Errorf from lib/errors and
prefers the stdlib errors package over lib/errors.

cmd/serve/docker/options.go

@@ -1,6 +1,7 @@
 package docker
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -12,7 +13,6 @@ import (
 	"github.com/rclone/rclone/vfs/vfscommon"
 	"github.com/rclone/rclone/vfs/vfsflags"
 
-	"github.com/pkg/errors"
 	"github.com/spf13/pflag"
 )
 
@@ -62,7 +62,7 @@ func (vol *Volume) applyOptions(volOpt VolOpts) error {
 		case "remote", "fs":
 			p, err := fspath.Parse(str)
 			if err != nil || p.Name == ":" {
-				return errors.Wrapf(err, "cannot parse path %q", str)
+				return fmt.Errorf("cannot parse path %q: %w", str, err)
 			}
 			fsName, fsPath, fsOpt = p.Name, p.Path, p.Config
 			vol.Fs = str
@@ -100,7 +100,7 @@ func (vol *Volume) applyOptions(volOpt VolOpts) error {
 	}
 	fsInfo, err := fs.Find(fsType)
 	if err != nil {
-		return errors.Errorf("unknown filesystem type %q", fsType)
+		return fmt.Errorf("unknown filesystem type %q", fsType)
 	}
 
 	// handle remaining options, override fsOpt
@@ -124,21 +124,21 @@ func (vol *Volume) applyOptions(volOpt VolOpts) error {
 			ok = true
 		}
 		if err != nil {
-			return errors.Wrapf(err, "cannot parse option %q", key)
+			return fmt.Errorf("cannot parse option %q: %w", key, err)
 		}
 
 		if !ok {
 			// try to use as a mount option in mntOpt
 			ok, err = getMountOption(mntOpt, opt, key)
 			if ok && err != nil {
-				return errors.Wrapf(err, "cannot parse mount option %q", key)
+				return fmt.Errorf("cannot parse mount option %q: %w", key, err)
 			}
 		}
 		if !ok {
 			// try as a vfs option in vfsOpt
 			ok, err = getVFSOption(vfsOpt, opt, key)
 			if ok && err != nil {
-				return errors.Wrapf(err, "cannot parse vfs option %q", key)
+				return fmt.Errorf("cannot parse vfs option %q: %w", key, err)
 			}
 		}
 
@@ -149,11 +149,11 @@ func (vol *Volume) applyOptions(volOpt VolOpts) error {
 			hasFsPrefix := optWithPrefix != fsOptName
 			if !hasFsPrefix || fsInfo.Options.Get(fsOptName) == nil {
 				fs.Logf(nil, "Option %q is not supported by backend %q", key, fsType)
-				return errors.Errorf("unsupported backend option %q", key)
+				return fmt.Errorf("unsupported backend option %q", key)
 			}
 			fsOpt[fsOptName], err = opt.GetString(key)
 			if err != nil {
-				return errors.Wrapf(err, "cannot parse backend option %q", key)
+				return fmt.Errorf("cannot parse backend option %q: %w", key, err)
 			}
 		}
 	}