Deals with Windows crash on PortAllocator cleanup
Release port_allocator to avoid segfaults
Changing timeout length to determine effect
Disable disconnection on WIN32 to avoid crash
Merge pull request #43 from ptony82/fix/windows_hardening

Fix/windows hardening
Fix memory leak in DestroyTransport.

Transport (and channels) depends on port_allocator, so we need delete
transport before deleting port_allocator.
The order of members in PeerState make default destructor to delete
port_allocator first, that may crash program in some situation.
Merge pull request #45 from kangjianbin/master

Fix memory leak in DestroyTransport.