First iteration of a Python tracer module

This module uses Python's sys.settrace() mechanism so setup a hook that can log every significant operation
This is a first step in providing a good debugging experience of Python embedded in LLDB
This module comprises an OO infrastructure that wraps Python's tracing and inspecting mechanisms, plus a very simple logging tracer
Output from this tracer looks like:

call print_keyword_args from <module> @ 243 args are kwargs are {'first_name': 'John', 'last_name': 'Doe'}
running print_keyword_args @ 228 locals are {'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}
running print_keyword_args @ 229 locals are {'key': 'first_name', 'value': 'John', 'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}
first_name = John
running print_keyword_args @ 228 locals are {'key': 'first_name', 'value': 'John', 'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}
running print_keyword_args @ 229 locals are {'key': 'last_name', 'value': 'Doe', 'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}
last_name = Doe
running print_keyword_args @ 228 locals are {'key': 'last_name', 'value': 'Doe', 'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}
return from print_keyword_args value is None locals are {'key': 'last_name', 'value': 'Doe', 'kwargs': {'first_name': 'John', 'last_name': 'Doe'}}

llvm-svn: 181343