build: Update Windows to Qt5.15 (#798)

* Update compile howto

- to qt5.15
- minimal install overhead
- sync with vscode and cmake

* Update docs with more input

gh actions windows: Qt5.15 and msvc2019

* fix: Azure build

.editorconfig

@@ -18,4 +18,8 @@ indent_size = 4
 # js and webui
 [*.{ts,js,html}]
 indent_style = space
-indent_size = 2
+indent_size = 2
+
+# version file
+[version]
+insert_final_newline = false