fix some cast warnings
remove file manager LRU cache from code.

This was a very clever attempt to fix a non-problem. If the platform doesn't have enough file descriptors available
then the platform is broken and we're not going to hack around trying to fix it.
Revert "fix some cast warnings"

This reverts commit 17707b9674958391949e59a724a264cdcc2d65ff.
Merge branch 'nofilemanager'