Create data folder when starting out

src/main/kotlin/net/deliciousreya/minecraftportal/MinecraftPortalPlugin.kt

@@ -33,6 +33,13 @@ class MinecraftPortalPlugin() : JavaPlugin(), Listener
 
     override fun onEnable() {
         super.onEnable()
+        if (!dataFolder.isDirectory) {
+            if (dataFolder.exists()) {
+                throw IllegalStateException("Data folder already exists but not as a directory")
+            } else {
+                dataFolder.mkdirs()
+            }
+        }
         portals.loadFromAndAutoSaveTo(server, dataFolder.resolve("portal_data.binproto"), dataFolder.resolve("portal_data.binproto.bak"))
         portals.validateWorldOnStartup(logger)
         portals.launchEffectsOnStartup(this)