Improve database abstractions, add GlobalAddedData, some other things

src/main/kotlin/io/dico/parcels2/command/CommandsGeneral.kt

@@ -4,6 +4,7 @@ import io.dico.dicore.command.EMessageType
 import io.dico.dicore.command.ExecutionContext
 import io.dico.dicore.command.annotation.Cmd
 import io.dico.dicore.command.annotation.Desc
+import io.dico.dicore.command.annotation.Flag
 import io.dico.dicore.command.annotation.RequireParameters
 import io.dico.parcels2.ParcelOwner
 import io.dico.parcels2.ParcelsPlugin
@@ -84,12 +85,22 @@ class CommandsGeneral(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
 
     @Cmd("clear")
     @ParcelRequire(owner = true)
-    fun ParcelScope.cmdClear(context: ExecutionContext) {
+    fun ParcelScope.cmdClear(context: ExecutionContext, @Flag sure: Boolean): Any? {
+        if (!sure) return "Are you sure? You cannot undo this action!\n" +
+            "Type ${context.rawInput} -sure if you want to go through with this."
+
         world.generator.clearParcel(parcel)
             .onProgressUpdate(1000, 1000) { progress, elapsedTime ->
                 context.sendMessage(EMessageType.INFORMATIVE, "Clear progress: %.02f%%, %.2fs elapsed"
                     .format(progress * 100, elapsedTime / 1000.0))
             }
+
+        return null
+    }
+
+    @Cmd("swap")
+    fun ParcelScope.cmdSwap(context: ExecutionContext, @Flag sure: Boolean): Any? {
+
     }
 
     @Cmd("make_mess")

src/main/kotlin/io/dico/parcels2/command/ParcelMatcher.kt

@@ -0,0 +1,23 @@
+package io.dico.parcels2.command
+
+import io.dico.parcels2.Parcel
+import io.dico.parcels2.ParcelWorld
+import io.dico.parcels2.ParcelsPlugin
+import kotlinx.coroutines.experimental.Deferred
+
+interface ParcelTarget {
+    val world: ParcelWorld
+    val isByID: Boolean
+    val isByOwner: Boolean get() = !isByID
+    suspend fun ParcelsPlugin.await(): Parcel?
+    fun ParcelsPlugin.get(): Deferred<Parcel?> =
+}
+
+class ParcelTargetByOwner : ParcelTarget {
+    override val isByID get() = false
+}
+
+class ParcelTargetByID : ParcelTarget {
+    override val isByID get() = true
+
+}

src/main/kotlin/io/dico/parcels2/command/ParcelParameterTypes.kt

@@ -7,6 +7,7 @@ import io.dico.dicore.command.parameter.type.ParameterConfig
 import io.dico.dicore.command.parameter.type.ParameterType
 import io.dico.parcels2.Parcel
 import io.dico.parcels2.ParcelWorld
+import io.dico.parcels2.ParcelsPlugin
 import io.dico.parcels2.Worlds
 import io.dico.parcels2.util.isValid
 import org.bukkit.Bukkit