windows: Unicode and IPv6 http/sockets

cleanup schannel implementation (drop NT4.0 compatibility, use unicode strings, etc)
restore http tests
fix socket test: it did not throw before

vlib/http/backend_win.v

@@ -8,6 +8,7 @@ module http
 #flag windows -I @VROOT/thirdparty/vschannel
 #flag -l ws2_32
 #flag -l crypt32
+#flag -l secur32
  
 #include "vschannel.c"
 
@@ -22,7 +23,7 @@ fn (req &Request) ssl_do(port int, method, host_name, path string) Response {
 	mut buff := malloc(C.vsc_init_resp_buff_size)
 	addr := host_name
 	sdata := req.build_request_headers(method, host_name, path)
-	length := int(C.request(&ctx, port, addr.str, sdata.str, &buff))
+	length := int(C.request(&ctx, port, addr.to_wide(), sdata.str, &buff))
 
 	C.vschannel_cleanup(&ctx)
 	return parse_response(string(buff, length))