Fix several deprecation warnings

- Switch to the new networking API, just doing sneaky things to make it
   the same as the old networking API.
 - Use new FabricLoader API
 - Don't use the static final game version, as this may change if people
   run the mod on newer versions.

build.gradle

@@ -237,13 +237,7 @@ task licenseFormatAPI(type: LicenseFormat)
 publishing {
     publications {
         mavenJava(MavenPublication) {
-            // add all the jars that should be included when publishing to maven
-            artifact(remapJar) {
-                builtBy remapJar
-            }
-            artifact(sourcesJar) {
-                builtBy remapSourcesJar
-            }
+            from components.java
         }
     }