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.

tst/editor/editor_driver.py

@@ -62,7 +62,9 @@ def main():
             out = run_cli(script, ['align', str(line), str(col)], s)
         else:
             sys.exit("editor_driver.py: unknown mode: " + mode)
-        with open(outfile, 'w') as f:
+        # newline='': the core's "\n" reaches the file untranslated on every
+        # system (text mode would write CRLF on Windows, against LF fixtures).
+        with open(outfile, 'w', newline='') as f:
             f.write(out)
 
     # Error and diagnostics paths.

tst/editor/vscode_ext_test.js

@@ -81,7 +81,9 @@ const vscodeStub = {
     Uri: { parse: (s) => ({ toString: () => s }) },
     DiagnosticSeverity: { Error: 0, Warning: 1 },
     workspace: {
-        getConfiguration: () => ({ get: (k) => (k === 'pythonPath' ? 'python3' : '') }),
+        // Both settings blank: the extension's own defaults are what is tested
+        // (python3, on Windows python; the server located by the search chain).
+        getConfiguration: () => ({ get: () => '' }),
         textDocuments: [fakeDoc],
         onDidOpenTextDocument: (fn) => { listeners.open.push(fn); return { dispose() {} }; },
         onDidChangeTextDocument: (fn) => { listeners.change.push(fn); return { dispose() {} }; },