Create theme dir if needed (#49)

- Use Path.Combine throughout
- Update theme versions
- Update generator version

src/MyWebLog/Program.fs

@@ -218,8 +218,9 @@ let main args =
         // Load admin and default themes, and all themes in the /themes directory
         do! Maintenance.loadTheme [| ""; "./admin-theme.zip"   |] app.Services
         do! Maintenance.loadTheme [| ""; "./default-theme.zip" |] app.Services
-        if Directory.Exists "./themes" then
-            for themeFile in Directory.EnumerateFiles("./themes", "*-theme.zip") do
+        let themePath = Path.Combine(".", "themes")
+        if Directory.Exists themePath then
+            for themeFile in Directory.EnumerateFiles(themePath, "*-theme.zip") do
                 do! Maintenance.loadTheme [| ""; themeFile |] app.Services
             
         let _ = app.UseForwardedHeaders()