Add similarity accessor to diff deltas

Author: tiennou

ObjectiveGit/GTDiffDelta.h

@@ -73,6 +73,8 @@ NS_ASSUME_NONNULL_BEGIN
 /// Think "status" as in `git status`.
 @property (nonatomic, readonly) GTDeltaType type;
 
+@property (nonatomic, readonly, assign) double similarity;
+
 /// Diffs the given blob and data buffer.
 ///
 /// oldBlob     - The blob which should comprise the left side of the diff. May be

ObjectiveGit/GTDiffDelta.m

@@ -59,6 +59,9 @@ - (GTDiffFile *)newFile {
 - (GTDeltaType)type {
 	return (GTDeltaType)self.git_diff_delta.status;
 }
+
+- (double)similarity {
+	return (double)(self.git_diff_delta.similarity / 100.0);
 }
 
 #pragma mark Lifecycle