support datagram unix domain sockets

test/unixtcpclnt.lua

@@ -1,6 +1,6 @@
 socket = require"socket"
 socket.unix = require"socket.unix"
-c = assert(socket.unix())
+c = assert(socket.unix.tcp())
 assert(c:connect("/tmp/foo"))
 while 1 do
     local l = io.read()

test/unixtcpsrvr.lua

@@ -1,6 +1,6 @@
     socket = require"socket"
     socket.unix = require"socket.unix"
-    u = assert(socket.unix())
+    u = assert(socket.unix.tcp())
     assert(u:bind("/tmp/foo"))
     assert(u:listen())
     c = assert(u:accept())

test/unixudpclnt.lua

@@ -0,0 +1,9 @@
+socket = require"socket"
+socket.unix = require"socket.unix"
+c = assert(socket.unix.udp())
+c:bind("/tmp/bar")
+while 1 do
+    local l = io.read("*l")
+    assert(c:sendto(l, "/tmp/foo"))
+	print(assert(c:receivefrom()))
+end

test/unixudpsrvr.lua

@@ -0,0 +1,9 @@
+    socket = require"socket"
+    socket.unix = require"socket.unix"
+    u = assert(socket.unix.udp())
+    assert(u:bind("/tmp/foo"))
+    while 1 do
+		x, r = assert(u:receivefrom())
+		print(x, r)
+		assert(u:sendto(">" .. x, r))
+    end