Add basic diff view

Finally, xdiff is used to show per-file diffs via commit view.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Makefile

@@ -6,7 +6,7 @@ CACHE_ROOT = /var/cache/cgit
 
 EXTLIBS = ../git/libgit.a ../git/xdiff/lib.a -lz -lcrypto
 OBJECTS = shared.o cache.o parsing.o html.o ui-shared.o ui-repolist.o \
-	ui-summary.o ui-log.o ui-view.c ui-tree.c ui-commit.c
+	ui-summary.o ui-log.o ui-view.c ui-tree.c ui-commit.c ui-diff.o
 
 CFLAGS += -Wall