Updates borger: 15c5389 Add ideas

diff --git a/borger b/borger
index 0136a6eb1714e935618d8b32fc4058980cd5e2d3..15c53893954a91d9f9eea890a2bbe0ff512f211f 160000 (submodule)
--- a/borger
+++ b/borger
@@ -1 +1 @@
-Subproject commit 0136a6eb1714e935618d8b32fc4058980cd5e2d3
+Subproject commit 15c53893954a91d9f9eea890a2bbe0ff512f211f