Context: do not let close() throw Exception

The dispose() method does not throw exceptions, and we do not need to throw
one when auto-closing. This prevents the compilation error:

  Unhandled exception type Exception thrown by automatic close() invocation on context

which occurs with code of the form:

  try (Context context = new Context()) {
    ...
  }

Author: ctrueden

src/main/java/org/scijava/Context.java

@@ -433,7 +433,7 @@ public void dispose() {
 	// -- AutoCloseable methods --
 
 	@Override
-	public void close() throws Exception {
+	public void close() {
 		dispose();
 	}