Add powershell library for common functions

windows/Dockerfile

@@ -121,3 +121,4 @@ RUN python -m pip --no-cache-dir install --no-warn-script-location \
         numpy \
         scipy \
         pandas
+COPY lib.ps1 C:/lib.ps1

windows/lib.ps1

+
+#
+# Sets up Visual Studio Development environment
+#
+function VSDevEnv {
+    pushd "C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/Common7/Tools"
+    cmd /c "VsDevCmd.bat $args & set" |
+    foreach {
+        if ($_ -match "=") {
+            $v = $_.split("="); set-item -force -path "ENV:\$($v[0])"  -value "$($v[1])"
+        }
+    }
+    popd
+}
+
+#
+# Sets exit to error when the command fails
+#
+function Must-Run {
+  $command = $args[0]
+  $arguments = $args[1..($args.Length)]
+  & $command @arguments
+  if (!$?) {
+    $Host.SetShouldExit(1)
+    Write-Error "Exit code $LastExitCode while running $command $arguments"
+    Exit(1)
+  }
+}