Windows: product names, the editors, WSL; the Linux page's image step

Assembled from development commit c3c40f6c8fca. Since 830b193: on Windows the
products carry Windows names (ktext.exe, klammertext.dll, document.dll,
reflect.dll) and the console's output code page is UTF-8 for a run; the
editor tooling works on Windows (VS Code, Sublime Text, Vim, with the
interpreter's name chosen by platform) and Notepad++ joins it
(doc/edit/notepadpp: a User Defined Language and two Run-menu commands);
a sixth install page, doc/install/windows_wsl_install.md, for Linux
inside WSL; the Windows page opens with the three routes and gains its
editor section, the PowerShell quoting and Path notes; the Linux page
installs OpenImageIO from the python3-openimageio package and verifies
with kdiag --machine; the README lists all six install pages. Linux and
macOS behaviour is unchanged.

README.md

@@ -11,6 +11,8 @@ Installation guides are in [`doc/install/`](doc/install/):
 
 - Linux, from source — `doc/install/linux_source_install.md`
 - macOS, from source — `doc/install/macos_source_install.md`
+- Windows, from source (native) — `doc/install/windows_source_install.md`
+- Windows, Linux inside WSL — `doc/install/windows_wsl_install.md`
 - Linux, container — `doc/install/linux_container_install.md`
 - macOS, container — `doc/install/macos_container_install.md`
 
@@ -51,7 +53,7 @@ are regenerated on each release — patches cannot be merged directly.
 Report problems (or send patches) to the author; accepted changes are
 applied to the development tree and appear in a following snapshot.
 
-This snapshot was assembled from development commit `f344a37d772c`.
+This snapshot was assembled from development commit `c3c40f6c8fca`.
 
 ## License