Support inter-thread blocks measuring

[Nizerlak]

Useful feature would be possibility of creating and tracking inter-thread blocks.
Possible use case:

• We want to track an object lifetime, which is passed or shared via std::shared_ptr between threads in app.
• On object creation, call to EASY_INTER_THREAD_BLOCK(/* object specific id */) would be performed.
• In object deleter (or custom shared_ptr deleter) there would be call to EASY_INTER_THREAD_BLOCK_END(/* object specific id */)
• GUI app would present the block lifetime in separate section (since it wouldn't be attached to specific thread obviously)

Of course above macros' names are only my suggestion and could be replaced by anything, it's only for presentation purpose.
What do you think about this feature?