v0.2.0

Main changes / breaking changes:

• weak_ptr is renamed to observer_ptr and no longer has a lock() function; you can just de-reference it like a normal pointer, and will get nullptr if the object has been deleted.
• The implementation no longer uses std::shared_ptr under the hood, so most of the limitations (e.g., type-erased deleter, no release()) have been lifted.

Small changes and bug fixes:

• fixed operator== not compiling for observable_unique_ptr
• fixed observer_ptr not constructible from derived type
• added memory leak tests
• added missing comparison operators for observer_ptr
• added missing operator bool()