index: Add API for unmerged entries

New external functions:
	- git_index_unmerged_entrycount: Counts the unmerged entries in
	  the index
	- git_index_get_unmerged: Gets an unmerged entry from the index
	  by name

New internal functions:
	- read_unmerged: Wrapper for read_unmerged_internal
	- read_unmerged_internal: Reads unmerged entries from the index
	  if the index has the INDEX_EXT_UNMERGED_SIG set
	- unmerged_srch: Search function for unmerged vector
	- unmerged_cmp: Compare function for unmerged vector

New data structures:
	- git_index now contains a git_vector unmerged that stores
	  unmerged entries
	- git_index_entry_unmerged: Representation of an unmerged file
	  entry. It represents all three versions of the file at the
	  same time, with one name, three modes and three OIDs

1 files changed, 2 insertions, 0 deletions

diff --git a/src/index.h b/src/index.h
index e1e752f7c..f2402fd71 100644
--- a/src/index.h
+++ b/src/index.h
@@ -29,6 +29,8 @@ struct git_index {
 
 	unsigned int on_disk:1;
 	git_index_tree *tree;
+
+	git_vector unmerged;
 };
 
 #endif