Hotfix for #696 and fix travis

Squashed commit of the following:

commit 741b2dd254
Author: Chloe Dawn <admin@designdevils.co.uk>
Date:   Mon May 13 16:40:38 2019 +0100

    Hotfix for #696

commit b88b9d5950
Author: modmuss50 <modmuss50@gmail.com>
Date:   Mon May 13 16:12:49 2019 +0100

    Disable email on build

commit f45e26dd01
Author: modmuss50 <modmuss50@gmail.com>
Date:   Mon May 13 16:09:21 2019 +0100

    fix travis?

.travis.yml

@@ -6,4 +6,7 @@ jdk:
 
 script:
   - chmod +x gradlew
-  - ./gradlew build mapNamedJar --stacktrace
+  - ./gradlew build mapNamedJar --stacktrace
+
+notifications:
+  email: false

gradle.properties

@@ -0,0 +1,2 @@
+# Done to increase the memory available to gradle.
+org.gradle.jvmargs=-Xmx1G

mappings/net/minecraft/block/entity/Hopper.mapping

@@ -5,5 +5,5 @@ CLASS bub net/minecraft/block/entity/Hopper
 	METHOD A getHopperY ()D
 	METHOD B getHopperZ ()D
 	METHOD O_ getInputAreaShape ()Lcsr;
-	METHOD w getWorld ()Lbhi;
+	METHOD w getHopperWorld ()Lbhi;
 	METHOD z getHopperX ()D