reload collections before deleting them

Two changes:

* Made `Storage.reload_collections` public (I needed it for the tests, and can think of other usages)
* Invoked `reload_collections` inside `delete_all`. This way if there are two concurrent jor drivers, one can erase the other's collections (the fact that the collection was erased does is not evident until `reload_collections` is invoked, but that's a bit difficult to do :) ). There is a new test for that.

The rest of the changes are white-space removal (my editor does those on save).