Webside<->GDB<->Pharo backend for C++ VM

[melkyades]

The plan for debugging C++ VM is:

• A developer could use plain GDB to debug the C++ VM, but debugging real problems takes a lot of work.
• Instead, here we implement a Webside backend that looks at the VM memory through GDB API (there already exist pharo bindings for GDB).
• The Webside backend serves requests from Webside clients that let developers look at high level information, such as object classes, method souces, processes, etc
• The Webside backend could also serve lower level information such as heap state, native code (if any), registers, C stack, etc.