Debian/oldstable docker container for packaging (#942)

This adds dockerized build stances to .gitlab-ci.yml. They will run only in scheduled builds (i.e. once per day at night) or upon special request (through secret GUI button). They shall ensure that at any time we are ready to generate binary installers.

This resolves #942 (closed).

.gitlab-ci.yml

@@ -170,7 +170,7 @@ windows:
     - echo "# PythonPath '<$Env:PYTHONPATH>'"
     - echo "# Powershell <$PSHOME>`n  PS Profile <$PROFILE>`n  PS Command-Path <$PSCOMMANDPATH>"
     # Visual Studio path <https://github.com/microsoft/vswhere/wiki/Find-VC>
-    - $vsPath = &"${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" -latest -products -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationpath
+    - $vsPath = &"${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationpath
     - echo "Microsoft Visual Studio path = '$vsPath'"
     - Import-Module (Get-ChildItem $vsPath -Recurse -File -Filter Microsoft.VisualStudio.DevShell.dll).FullName
     - Enter-VsDevShell -VsInstallPath $vsPath -SkipAutomaticLocation -DevCmdArguments '-arch=x64'