Re-introduce Superclass Transformer

[gabizou]

Goal

Reintroduces the ability to re-assign the superclass of a target class previously achieved in legacy launch wrapper transformers. Certain API based classes have a requirement at runtime to be extensions of implementation classes.

Solution

The new transformer setup also pulls out the AccessWidener transformer to be available for both Vanilla and Forge without depending on either.

An example of changing org.spongepowered.api.entity.ai.goal.AbstractGoal from java.lang.Object:
In SpongeForge:

     protected AbstractGoal(org.spongepowered.api.entity.ai.goal.GoalType arg0) { // <init> //(Lorg/spongepowered/api/entity/ai/goal/GoalType;)V
         <localVar:index=0 , name=this , desc=Lorg/spongepowered/api/entity/ai/goal/AbstractGoal;, sig=Lorg/spongepowered/api/entity/ai/goal/AbstractGoal<TO;>;, start=L1, end=L2>
         <localVar:index=1 , name=type , desc=Lorg/spongepowered/api/entity/ai/goal/GoalType;, sig=null, start=L1, end=L2>

         L1 {
             aload0 // reference to self
             invokespecial net/minecraft/entity/ai/goal/Goal.<init>()V
         }

In SpongeVanilla:

     protected AbstractGoal(org.spongepowered.api.entity.ai.goal.GoalType arg0) { // <init> //(Lorg/spongepowered/api/entity/ai/goal/GoalType;)V
         <localVar:index=0 , name=this , desc=Lorg/spongepowered/api/entity/ai/goal/AbstractGoal;, sig=Lorg/spongepowered/api/entity/ai/goal/AbstractGoal<TO;>;, start=L1, end=L2>
         <localVar:index=1 , name=type , desc=Lorg/spongepowered/api/entity/ai/goal/GoalType;, sig=null, start=L1, end=L2>

         L1 {
             aload0 // reference to self
             invokespecial net/minecraft/world/entity/ai/goal/Goal.<init>()V
         }

Caveats

• Pretty dumb transformer that doesn't handle remapping
• Buildscript isn't tidy or self isolated, could probably build modlauncher-transformers as a separated jar
• AccessWideners is only remapped by SpongeForge, not modlauncher-transformers