C#3.0 / .NET 3.5 and search tweak

I updated the server-side code to C# 3.0 and have it using the .NET 3.5 runtime now; this should result in precisely zero changes, but it's possible that I broke something. Let me know.

I also made two extremely minor search tweaks:
  • ? and _ now work as wildcard characters, matching exactly one character. This in addition to * and % which match zero or more characters.
  • Using uwp: prefix and wildcards are now mentioned in the "tool tip" when you hover over the search field. Previously these were mentioned only in the API docs.