Fix unique world sql error

Fix error thrown by unique constrain for the world name in the sql table. The error occurs because the data from the database is loaded lazily after several seconds. If a task was started before that it wouldn't be checked against the existing tasks since they haven't been loaded yet. Fixed by loading the tasks if none exists when the generate command is invoked.

src/main/kotlin/net/trivernis/chunkmaster/lib/generation/GenerationManager.kt

@@ -12,6 +12,12 @@ class GenerationManager(private val chunkmaster: Chunkmaster, private val server
     val pausedTasks: HashSet<PausedTaskEntry> = HashSet()
     val allTasks: HashSet<TaskEntry>
         get() {
+            if (this.tasks.isEmpty() && this.pausedTasks.isEmpty()) {
+                this.startAll()
+                if (!server.onlinePlayers.isEmpty()) {
+                    this.pauseAll()
+                }
+            }
             val all = HashSet<TaskEntry>()
             all.addAll(pausedTasks)
             all.addAll(tasks)
@@ -141,8 +147,9 @@ class GenerationManager(private val chunkmaster: Chunkmaster, private val server
             saveProgress()      // save progress every 30 seconds
         }, 600, 600)
         server.scheduler.runTaskLater(chunkmaster, Runnable {
-            if (server.onlinePlayers.isEmpty()) {
-                startAll()     // run startAll after 10 seconds if empty
+            this.startAll()
+            if (!server.onlinePlayers.isEmpty()) {
+                this.pauseAll()
             }
         }, 600)
     }