Merge numerous (small) improvements from rs/SDURLCache.

diff --git a/SDURLCache b/SDURLCache
index 964596be054e329b422f96fe8d0a01049ceb0551..894a1b139f21e85e28a235bb97b1654923ce3d72 160000 (submodule)
--- a/SDURLCache
+++ b/SDURLCache
@@ -1 +1 @@
-Subproject commit 964596be054e329b422f96fe8d0a01049ceb0551
+Subproject commit 894a1b139f21e85e28a235bb97b1654923ce3d72