Java 9 Patch

A quick compatibility patch for testing Java 9 with ATL packs. This simple patch adds a java 9 checker based on on the Java 8 checker, and gives Java 9 the correct arguments when detected. 



"-XX:+CMSIncrementalMode" also needs to me removed (via custom arguments) for Minecraft to launch with Java 9, which should stop average users from running a beta Java build ;)