Remove the old route when add blackhole route;

Refine the code;
List issues in the README.cygwin;

Change the data type of destination and gate in the kernel_route;
Set blackhole interface index to 1;
Clear pipe data after checking route table.

Restore KERNEL_IFINITY from 9999 to 0xFFFF;
Add function libwinet_map_ifindex used to map interface index
between ipv4 and ipv6.

verify the functions in the cyginet.c
Remove "nexthop" from "netsh" commoand if ipv6 gate is empty.
Add function cyginet_ipv4_index2ifname

define KERNEL_IFNINITY as 9999 other than 0xFFFF as the same reason;
Use connection name as interface name instead GUID;
Add platform macro in the Makefile and source files;
Update README.cygwin as the changes.

Fix issues to get the route table.
Add README.cygwin

Add patches of Cygwin.

Add subdirectory 'cygwin' in the component/slapos, push all the patches and scripts for cygwin here.

Conflicts:
	component/slapos/buildout.cfg

WARNING: require recent slapos.core.

Misread code. So this change doesn't change anything.

This reverts commit 925f0cff.