Add stackman in Debugging / Profiling section

When writing custom error loggers, Stackman gives you easy access to the V8 internals of the Error object. Besides the standard functions on a V8 callsite object, with Stackman you get a lot of extra features: For instance access to the actual source code and surrounding lines for where the error occurred, you get to know if it happened inside a 3rd party module, in Node.js or in your own code.