Initial implementation of scope guard logging for including in crash logs.

This adds a mechanism to create scope guards with an associated std::function
which is called to output diagnostic info in the event of a crash.
Add a macro to make it easy to efficiently capture variables on the stack
and output a formatted message.
Requires C++11, #ifdefed out for legacy compilers.

source.list

@@ -1194,3 +1194,6 @@ thread/thread.h
 #else
 	thread/thread_none.cpp
 #end
+
+scope_info.cpp
+scope_info.h