context menu should not be available on closed projects

[Bananeweizen]

At least the "Create Formatter profile" menu throws an exception when invoked on a closed project:

java.lang.Exception: Project 'checkstyle' is not open.
	at org.eclipse.core.internal.resources.ResourceException.provideStackTrace(ResourceException.java:42)
	at org.eclipse.core.internal.resources.ResourceException.<init>(ResourceException.java:38)
	at org.eclipse.core.internal.resources.Project.checkAccessible(Project.java:153)
	at org.eclipse.core.internal.resources.File.create(File.java:112)
	at org.eclipse.core.internal.resources.File.create(File.java:181)
	at net.sf.eclipsecs.core.transformer.FormatterConfigWriter.createOrUpdateFile(FormatterConfigWriter.java:114)
	at net.sf.eclipsecs.core.transformer.FormatterConfigWriter.writeFormatterSettings(FormatterConfigWriter.java:103)
	at net.sf.eclipsecs.core.transformer.FormatterConfigWriter.writeSettings(FormatterConfigWriter.java:72)
	at net.sf.eclipsecs.core.transformer.FormatterConfigWriter.<init>(FormatterConfigWriter.java:64)
	at net.sf.eclipsecs.core.transformer.CheckstyleTransformer.transformRules(CheckstyleTransformer.java:124)
	at net.sf.eclipsecs.core.jobs.TransformCheckstyleRulesJob.runInWorkspace(TransformCheckstyleRulesJob.java:116)
	at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:43)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)