QCoro 0.5.0

• .then() continuation for Task<T> (#39)
• Fixed namespace scoping (#45)
• Fixed QCoro::waitFor() getting stuck when coroutine returns synchronously (#46)
• Fixed -pthread usage in CMake (#47)
• Produce QMake config files (.pri) for each module (commit e215616)
• Fix build on platforms where -latomic must be linked explicitly (#52)
• Return Task<T> from all operations (#54)
• Add QCoro wrapper for QThread (commit 832d931)
• Many documentation updates