attempt to handle java sorting priorities by MC version

settings.getCurrentJava() is used in a lot of places -- still needs some more thought into a more reliable way to do this
ADDED:  java8 error messages

 * Show error message if old pack is started with java 8
 * Java 8 checks can be overridded with command line argument
CHANGED: log link if OSUtils.browse() fails
ADDED: todo for later
Merge pull request #865 from jikuja/java8sorting

Java8sorting