move plumbing from top level package to plumbing (#183)

* plumbing: rename Object -> EncodedObject.

* plumbing/storer: rename ObjectStorer -> EncodedObjectStorer.

* move difftree to plumbing/difftree.

* move diff -> utils/diff

* make Object/Tag/Blob/Tree/Commit/File depend on storer.

* Object and its implementations now depend only on
  storer.EncodedObjectStorer, not git.Repository.
* Tests are decoupled accordingly.

* move Object/Commit/File/Tag/Tree to plumbing/object.

* move Object/Commit/File/Tag/Tree to plumbing/object.
* move checkClose to utils/ioutil.

* move RevListObjects to plumbing/revlist.Objects.

* move DiffTree to plumbing/difftree package.

* rename files with plural nouns to singular

* plumbing/object: add GetBlob/GetCommit/GetTag/GetTree.

1 files changed, 0 insertions, 65 deletions

diff --git a/difftree/internal/merkletrie/node.go b/difftree/internal/merkletrie/node.go
deleted file mode 100644
index 99be5b8..0000000
--- a/difftree/internal/merkletrie/node.go
+++ /dev/null
@@ -1,65 +0,0 @@
-package merkletrie
-
-import (
-	"sort"
-	"strings"
-)
-
-// A node is a Noder implementation for testing purposes:  It is easier
-// to create test trees using nodes than using real git tree objects.
-type node struct {
-	hash     []byte
-	key      string
-	children []*node
-}
-
-// newNode returns a new Node with the given hash, key and children
-// (children can be specified in any order).
-func newNode(hash []byte, key string, children []*node) *node {
-	sort.Sort(reverseAlphabeticallyByKey(children))
-
-	return &node{
-		hash:     hash,
-		key:      key,
-		children: children,
-	}
-}
-
-// Hash returns the hash of the node.
-func (n *node) Hash() []byte {
-	return n.hash
-}
-
-// Key returns the key of the node.
-func (n *node) Key() string {
-	return n.key
-}
-
-// NumChildren returns the number of children.
-func (n *node) NumChildren() int {
-	return len(n.children)
-}
-
-// Children returns the node's children in reverse key alphabetical
-// order.
-func (n *node) Children() []Noder {
-	ret := make([]Noder, n.NumChildren())
-	for i := range n.children {
-		ret[i] = n.children[i]
-	}
-	return ret
-}
-
-type reverseAlphabeticallyByKey []*node
-
-func (a reverseAlphabeticallyByKey) Len() int {
-	return len(a)
-}
-
-func (a reverseAlphabeticallyByKey) Swap(i, j int) {
-	a[i], a[j] = a[j], a[i]
-}
-
-func (a reverseAlphabeticallyByKey) Less(i, j int) bool {
-	return strings.Compare(a[i].key, a[j].key) > 0
-}