Optimize SSLProtocol write backlog operations

[tarasko]

• Use list to implement write backlog queue in SSLProtocol. Comparing to collections.Deque, which is an opaque type for cython, list is transparent for cython. Cython offers a lot of optimizations for list type.
• SSLProtocol._do_write do not popfront on every iteration. Instead everything that was sent is deleted in one go in the end
• Make SSL write and writelines consistent with regards to user data type checking
• Consistently use Py_ssize_t instead of size_t/ssize_t/int to avoid implicit conversions. Py_ssize_t is what python PyList_SIZE and others return
• Remove extra tuple creation and unpacking in write
• Fix warning: uvloop/handles/pipe.pyx:159:4: Overriding a c(p)def method with a def method.