Fix an issue with pythons scripts running outside Kicad (Windows specific).

When running a python script is run from a console, outside Kicad, a wxWidgets
alert was always show (even in release mode)
This is due to calling wxStandardPaths::Get() with no wxApp open( i.e. wxTheApp == O)
The fix uses a dummy wxApp in this case.

libs/kiplatform/msw/environment.cpp

@@ -28,6 +28,8 @@
 #include <shellapi.h>
 #include <shlwapi.h>
 
+#include <wx/app.h>
+
 
 void KIPLATFORM::ENV::Init()
 {
@@ -69,12 +71,28 @@ bool KIPLATFORM::ENV::IsNetworkPath( const wxString& aPath )
 
 wxString KIPLATFORM::ENV::GetDocumentsPath()
 {
+    // If called by a python script in stand-alone (outside kicad), wxStandardPaths::Get()
+    // complains about not existing app. so use a dummy app
+    if( wxTheApp ==  nullptr )
+    {
+        wxApp dummy;
+        return wxStandardPaths::Get().GetDocumentsDir();
+    }
+
     return wxStandardPaths::Get().GetDocumentsDir();
 }
 
 
 wxString KIPLATFORM::ENV::GetUserConfigPath()
 {
+    // If called by a python script in stand-alone (outside kicad), wxStandardPaths::Get()
+    // complains about not existing app. so use a dummy app
+    if( wxTheApp ==  nullptr )
+    {
+        wxApp dummy;
+        return wxStandardPaths::Get().GetUserConfigDir();
+    }
+
     return wxStandardPaths::Get().GetUserConfigDir();
 }
 
@@ -84,6 +102,17 @@ wxString KIPLATFORM::ENV::GetUserCachePath()
     // Unfortunately AppData/Local is the closest analog to "Cache" directories of other platforms
 
     // Make sure we dont include the "appinfo" (appended app name)
+
+    // If called by a python script in stand-alone (outside kicad), wxStandardPaths::Get()
+    // complains about not existing app. so use a dummy app
+    if( wxTheApp ==  nullptr )
+    {
+        wxApp dummy;
+        wxStandardPaths::Get().UseAppInfo( wxStandardPaths::AppInfo_None );
+
+        return wxStandardPaths::Get().GetUserLocalDataDir();
+   }
+
     wxStandardPaths::Get().UseAppInfo( wxStandardPaths::AppInfo_None );
 
     return wxStandardPaths::Get().GetUserLocalDataDir();