The article "How to add a new Operator" contains several dead links

The documentation about the implementation of new operators which is available at http://flink.incubator.apache.org/docs/0.7-incubating/internal_add_operator.html contains several dead links.

At least the following:

• "Program Life Cycle" (pointing to http://flink.incubator.apache.org/docs/0.7-incubating/program_life_cycle.html)
• "Driver" (pointing to https://github.com/apache/incubator-flink/blob/master//flink-runtime/src/main/java/org/apache/flink/pact/runtime/task/PactDriver.java)
• "MapDriver" (pointing to https://github.com/apache/incubator-flink/blob/master//flink-runtime/src/main/java/org/apache/flink/pact/runtime/task/MapDriver.java)
• "ChainedMapDriver" (pointing to https://github.com/apache/incubator-flink/blob/master//flink-runtime/src/main/java/org/apache/flink/pact/runtime/task/chaining/ChainedMapDriver.java)
• "Optimizer" (pointing to http://flink.incubator.apache.org/docs/0.7-incubating/optimizer.html)
• "DriverStrategy" (pointing to https://github.com/apache/incubator-flink/blob/master//flink-runtime/src/main/java/org/apache/flink/pact/runtime/task/DriverStrategy.java)