Rename rawsockets module to nativesockets

This change was done to avoid confusion with TCP/IP raw sockets. Native sockets
module represents handling native system low level socket API in general and is
not just limited anyhow to TCP/IP raw sockets.

A stub lib/deprecated/pure/rawsockets.nim module has been added as
compatibility layer for old code using rawsockets, so this change will not
break existing code.

tests/async/tasyncawait.nim

@@ -2,7 +2,7 @@ discard """
   file: "tasyncawait.nim"
   output: "5000"
 """
-import asyncdispatch, rawsockets, net, strutils, os
+import asyncdispatch, nativesockets, net, strutils, os
 
 var msgCount = 0
 
@@ -18,7 +18,7 @@ proc sendMessages(client: TAsyncFD) {.async.} =
 
 proc launchSwarm(port: TPort) {.async.} =
   for i in 0 .. <swarmSize:
-    var sock = newAsyncRawSocket()
+    var sock = newAsyncNativeSocket()
 
     await connect(sock, "localhost", port)
     await sendMessages(sock)
@@ -38,7 +38,7 @@ proc readMessages(client: TAsyncFD) {.async.} =
         doAssert false
 
 proc createServer(port: TPort) {.async.} =
-  var server = newAsyncRawSocket()
+  var server = newAsyncNativeSocket()
   block:
     var name: Sockaddr_in
     when defined(windows):

tests/async/tasyncconnect.nim

@@ -19,7 +19,7 @@ when defined(windows) or defined(nimdoc):
     quit("Error: unhandled exception: Connection refused")
 else:
     proc testAsyncConnect() {.async.} =
-        var s = newAsyncRawSocket()
+        var s = newAsyncNativeSocket()
 
         await s.connect(testHost, testPort)
 

tests/async/tasynceverror.nim

@@ -7,7 +7,7 @@ discard """
 import
     asyncdispatch,
     asyncnet,
-    rawsockets,
+    nativesockets,
     os
 
 
@@ -21,7 +21,7 @@ when defined(windows) or defined(nimdoc):
     quit("Error: unhandled exception: Connection reset by peer")
 else:
     proc createListenSocket(host: string, port: Port): TAsyncFD =
-        result = newAsyncRawSocket()
+        result = newAsyncNativeSocket()
 
         SocketHandle(result).setSockOptInt(SOL_SOCKET, SO_REUSEADDR, 1)