Add ui-shared.h

This is finally a proper headerfile for the shared ui-functions which
used to reside in cgit.h

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/ui-log.c b/ui-log.c
index e1d324d..60c9269 100644
--- a/ui-log.c
+++ b/ui-log.c
@@ -8,6 +8,7 @@
 
 #include "cgit.h"
 #include "html.h"
+#include "ui-shared.h"
 
 int files, add_lines, rem_lines;