Allow portals to be any Material type, don't limit to only isBlock()
Revert "Allow portals to be any Material type, don't limit to only isBlock()"

This reverts commit 512c6da16359c7bc0b12aa09f7bcd16e1d1f2dff.
Migration to SnakeYaml for save/load WarpPortal persistance using proper YAML
Version 4.3.0.3