Add soft dependency for Multiverse compatibility

If ES gets enabled before Multiverse does, ESSystems in worlds other
than the default will misbehave, because Multiverse hasn't loaded their
worlds yet. This means getWorld() returns null for those worlds and the
Location baked into the ESSystem is wrong.

Adding a soft dependency on MV-Core ensures that ES gets enabled after
MV, and thus, after all the game worlds are loaded.

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>net.seanomik</groupId>
     <artifactId>energeticstorage</artifactId>
-    <version>0.2-SNAPSHOT</version>
+    <version>0.2.1-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>EnergeticStorage</name>

src/main/resources/plugin.yml

@@ -3,6 +3,7 @@ version: ${project.version}
 main: net.seanomik.energeticstorage.EnergeticStorage
 api-version: 1.15
 authors: [SeanOMik]
+softdepend: [Multiverse-Core]
 commands:
   esgive:
     aliases: [egive]