add some localizations

Plugin/src/main/resources/assets/nt-rpg/localizations/localization_en.properties

@@ -123,3 +123,9 @@ rpg.main.player_invited_to_party_party_msg={{player}} &5 invited to the party
 rpg.main.player_invited_to_party={{player}} &2invited you to the party
 rpg.main.insufficient_level_gap=You need at least level {{level}} to be able to upgrade the skill.
 rpg.main.cannot_use_item_configuration_reason_offhand=&4You are not trained to dual wield with this weapon
+rpg.main.missing_class_dependencies=Class cannot be selected, missing its pre-requirements
+rpg.main.class_has_no_skilltree=Class {{class}} has no skill tree
+rpg.main.not_allowed_manual_skilltree_management=Class {{class}} have not allowed manual skill management
+rpg.main.refund_skills_depending=Not possible to refund skill, refund depending skills first
+rpg.main.unable_to_refund_skill=Not possible to refund skill
+rpg.main.unable_to_refund_skill_sealed=The skill node is sealed, may not be refunded.