Fix more warnings and do some small optimizations (#1356)

* Fix more warnings and do some small optimizations

* Fix more warnings in ValueConversions

* Clean up some decompiler names and fix an unnecessary transformation around commands

* Use (way) more compact data structure for slot map

* Minor tweaks
Such as map directly in the collector

* I hate vanilla javac
Revert map changes in latest commit

src/main/java/carpet/helpers/FeatureGenerator.java

@@ -158,7 +158,7 @@ public class FeatureGenerator
     private static Thing simpleTree(TreeConfiguration config)
     {
         //config.ignoreFluidCheck();
-        return simplePlop(new ConfiguredFeature(Feature.TREE, config));
+        return simplePlop(new ConfiguredFeature<>(Feature.TREE, config));
     }
 
     private static Thing spawnCustomStructure(Structure structure)