finish tool can use 'nimgrab' tool to download the mingw version

tools/finish.nim

@@ -30,8 +30,12 @@ proc unzip(): bool =
 
 proc downloadMingw(): DownloadResult =
   let curl = findExe"curl"
+  var cmd: string
   if curl.len > 0:
-    let cmd = curl & " --out " & "dist" / mingw & " " & url
+    cmd = curl & " --out " & "dist" / mingw & " " & url
+  elif fileExists"bin/nimgrab.exe":
+    cmd = "bin/nimgrab.exe " & url & " dist" / mingw
+  if cmd.len > 0:
     if execShellCmd(cmd) != 0:
       echo "download failed! ", cmd
       openDefaultBrowser(url)

tools/nimgrab.nim

@@ -0,0 +1,17 @@
+
+import os, asyncdispatch, httpclient
+
+proc syncDownload(url, file: string) =
+  var client = newHttpClient()
+  proc onProgressChanged(total, progress, speed: BiggestInt) =
+    echo "Downloading " & url & " " & $(speed div 1000) & "kb/s"
+    echo clamp(int(progress*100 div total), 0, 100), "%"
+
+  client.onProgressChanged = onProgressChanged
+  client.downloadFile(url, file)
+  echo "100%"
+
+if os.paramCount() != 2:
+  quit "Usage: nimgrab <url> <file>"
+else:
+  syncDownload(os.paramStr(1), os.paramStr(2))