<rdar://problem/13491977>

Made some fixes to the OperatingSystemPython class:
- If any thread dictionary contains any "core=N" key/value pairs then the threads obtained from the lldb_private::Process itself will be placed inside the ThreadMemory threads and will be used to get the information for a thread. 
- Cleaned up all the places where a thread inside a thread was causing problems

llvm-svn: 179405