[DO NOT MERGE] Poor main attempt to battle thread safety

[leotsarev]

Instead of approach in #24 (basically synchronize all access to ObjectContainer), i tried another approach.
Idea is to instead of container to synchronize access itself, it attempts synchronize access to parent container between other child containers. It not 100% solution (because those who use parent container directly will have to be careful to participate in synchronization, but in theory it will be more performant than #24 (because if you only one using container, you don't need to pay for synchronization). I need to way to check if this is actually win for Specflow's usecase (may be not, cause Specflow use a long chain of containers).

I'm planning to benchmark every solution, but I have not settled on right profile.

This and #24 has a problem of holding the container-wide lock during construction of object. It could be very costly if your constructors are heavy.