Create parser skeleton and utilities

gitdiff/gitdiff.go

@@ -0,0 +1,10 @@
+package gitdiff
+
+// File describes changes to a single file. It can be either a text file or a
+// binary file.
+type File struct {
+	Fragments []*Fragment
+}
+
+// Fragment describes changed lines starting at a specific line in a text file.
+type Fragment struct{}