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.

backend/compress/compress.go

@@ -10,6 +10,7 @@ import (
 	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -21,7 +22,6 @@ import (
 	"github.com/buengese/sgzip"
 	"github.com/gabriel-vasile/mimetype"
 
-	"github.com/pkg/errors"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/accounting"
 	"github.com/rclone/rclone/fs/chunkedreader"
@@ -143,7 +143,7 @@ func NewFs(ctx context.Context, name, rpath string, m configmap.Mapper) (fs.Fs,
 
 	wInfo, wName, wPath, wConfig, err := fs.ConfigFs(remote)
 	if err != nil {
-		return nil, errors.Wrapf(err, "failed to parse remote %q to wrap", remote)
+		return nil, fmt.Errorf("failed to parse remote %q to wrap: %w", remote, err)
 	}
 
 	// Strip trailing slashes if they exist in rpath
@@ -158,7 +158,7 @@ func NewFs(ctx context.Context, name, rpath string, m configmap.Mapper) (fs.Fs,
 		wrappedFs, err = wInfo.NewFs(ctx, wName, remotePath, wConfig)
 	}
 	if err != nil && err != fs.ErrorIsFile {
-		return nil, errors.Wrapf(err, "failed to make remote %s:%q to wrap", wName, remotePath)
+		return nil, fmt.Errorf("failed to make remote %s:%q to wrap: %w", wName, remotePath, err)
 	}
 
 	// Create the wrapping fs
@@ -304,7 +304,7 @@ func (f *Fs) processEntries(entries fs.DirEntries) (newEntries fs.DirEntries, er
 		case fs.Directory:
 			f.addDir(&newEntries, x)
 		default:
-			return nil, errors.Errorf("Unknown object type %T", entry)
+			return nil, fmt.Errorf("Unknown object type %T", entry)
 		}
 	}
 	return newEntries, nil
@@ -410,7 +410,7 @@ func (f *Fs) verifyObjectHash(ctx context.Context, o fs.Object, hasher *hash.Mul
 	srcHash := hasher.Sums()[ht]
 	dstHash, err := o.Hash(ctx, ht)
 	if err != nil {
-		return errors.Wrap(err, "failed to read destination hash")
+		return fmt.Errorf("failed to read destination hash: %w", err)
 	}
 	if srcHash != "" && dstHash != "" && srcHash != dstHash {
 		// remove object
@@ -418,7 +418,7 @@ func (f *Fs) verifyObjectHash(ctx context.Context, o fs.Object, hasher *hash.Mul
 		if err != nil {
 			fs.Errorf(o, "Failed to remove corrupted object: %v", err)
 		}
-		return errors.Errorf("corrupted on transfer: %v compressed hashes differ %q vs %q", ht, srcHash, dstHash)
+		return fmt.Errorf("corrupted on transfer: %v compressed hashes differ %q vs %q", ht, srcHash, dstHash)
 	}
 	return nil
 }
@@ -462,10 +462,10 @@ func (f *Fs) rcat(ctx context.Context, dstFileName string, in io.ReadCloser, mod
 		_ = os.Remove(tempFile.Name())
 	}()
 	if err != nil {
-		return nil, errors.Wrap(err, "Failed to create temporary local FS to spool file")
+		return nil, fmt.Errorf("Failed to create temporary local FS to spool file: %w", err)
 	}
 	if _, err = io.Copy(tempFile, in); err != nil {
-		return nil, errors.Wrap(err, "Failed to write temporary local file")
+		return nil, fmt.Errorf("Failed to write temporary local file: %w", err)
 	}
 	if _, err = tempFile.Seek(0, 0); err != nil {
 		return nil, err
@@ -714,7 +714,7 @@ func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, opt
 	if found && (oldObj.(*Object).meta.Mode != Uncompressed || compressible) {
 		err = oldObj.(*Object).Object.Remove(ctx)
 		if err != nil {
-			return nil, errors.Wrap(err, "Could remove original object")
+			return nil, fmt.Errorf("Could remove original object: %w", err)
 		}
 	}
 
@@ -723,7 +723,7 @@ func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, opt
 	if compressible {
 		wrapObj, err := operations.Move(ctx, f.Fs, nil, f.dataName(src.Remote(), newObj.size, compressible), newObj.Object)
 		if err != nil {
-			return nil, errors.Wrap(err, "Couldn't rename streamed Object.")
+			return nil, fmt.Errorf("Couldn't rename streamed Object.: %w", err)
 		}
 		newObj.Object = wrapObj
 	}