Various improvements to packaging

This fixes several issues I had with consuming multi-loader CC:T in
various upstream mods.

 - Include /all/ sources in the Forge/Fabric jar. Before it was just the
   common classes, and not the core or API.

 - Use some Gradle magic to remove superfluous dependencies from the POM
   file. Also make sure Cobalt and Netty are present as dependencies.

 - Start using minimize() in our shadow jar config again.

buildSrc/src/main/kotlin/cc/tweaked/gradle/Extensions.kt

@@ -1,8 +1,15 @@
 package cc.tweaked.gradle
 
+import org.gradle.api.artifacts.ResolvedDependency
 import org.gradle.api.artifacts.dsl.DependencyHandler
+import org.gradle.api.publish.maven.MavenPublication
+import org.gradle.api.specs.Spec
 import org.gradle.api.tasks.JavaExec
+import org.gradle.process.JavaExecSpec
 
+/**
+ * Add an annotation processor to all source sets.
+ */
 fun DependencyHandler.annotationProcessorEverywhere(dep: Any) {
     add("compileOnly", dep)
     add("annotationProcessor", dep)
@@ -14,6 +21,9 @@ fun DependencyHandler.annotationProcessorEverywhere(dep: Any) {
     add("testAnnotationProcessor", dep)
 }
 
+/**
+ * A version of [JavaExecSpec.copyTo] which copies *all* properties.
+ */
 fun JavaExec.copyToFull(spec: JavaExec) {
     copyTo(spec)
     spec.classpath = classpath