ci: attempt a action based build

ci: add workflow_dispatch


ci: adjust msys install instructions


ci: switch msystem


ci: try different cmake installation


ci: try mingw64 instead


ci: unix makefiles?


ci: switch to mingw64 shell


ci: install cmake via pacboy?


ci: switch to Ninja?


misc: remove some outdated XP compatibility preprocessor symbols?

https://docs.wxwidgets.org/trunk/page_wxusedef.html
ci: switch main to master


misc: more attempts at correcting build errors


misc: bitmap/image conversions?


ci: trying to get a static build


ci: try to find hunspell dll


ci: hunt down hunspell


ci: modify static flags

src/gui/value/choice.cpp

@@ -58,7 +58,7 @@ void ChoiceThumbnailRequest::store(const Image& img) {
   if (img.Ok()) {
     ChoiceThumbnail& thumbnail = style().thumbnails[id];
     ChoiceThumbnailLock lock(thumbnail.mutex);
-    thumbnail.bitmap = img;
+    thumbnail.bitmap = wxBitmap(img, -1);
     thumbnail.status = THUMB_OK;
   }
 }