Removed and replaced some calls to deprecated methods

This makes the code compile cleanly using both Scala 2.9 and 2.10
Added an adapter factory to provide CoqTopContainers for Java editors
Made the goal viewer use getAdapter to retrieve CoqTopContainers

This removes the special handling for the Java editor: now anything can
show goals in the goal viewer
Separated the GoalViewer's presentation code into a separate class

In future, we might want to allow more than one presentation strategy for
Coq goals
Added a handler for single-stepping forwards through a Java proof
Moved the goal viewer and its support code into a new file