Better __repr__ implementation of the Python debugger objects

[xusheng6]

Currently, if we print the various Python debugger objects, many of them do not give us any interesting information. For example,

>>> dbg

<debugger.debuggercontroller.DebuggerController object at 0x113e5c5b0>

We should give more information about the object.

Here is a list of the objects that we need to improve:

• [ ] DebuggerController
• [ ] DebugBreakpoint
• [ ] DebugThread
• [ ] DebugModule
• [x] DebugRegister
• [ ] DebugFrame
• [ ] DebugEvent
• [ ] etc