Fixed some parent fields like Instant Death Damage Limit not properly applying.

- Tweaked relationships (fixed resetting, added missing relationship types to other creatures, tweaked parent defaults, creatures' descendants are longer affected for simplicity).
- Tweaked parent defaults, added an "Apply Parent" button.
- "Inherit" no longer requires restarting the game.
- Removed implicit "Centipede" parent.
- Added warning colors to "Save File" and "Save Relationships" buttons.