Calico reset shell resets all languages; F# uses too many files

[Doug Blank]

I just ran out of open files; I think when we "reset shell" we reset all engines, and F# is using up a bunch of file handles (all of the references, I think).

$ calico 
Loading Calico version 3.0.0...

(Calico:19799): GLib-GObject-WARNING **: Attempt to add property __gtksharp_1_Mono_TextEditor_TextEditor::im-module after class was initialised

Unhandled Exception:
System.IO.IOException: Too many open files
  at System.IO.Directory.GetFileSystemEntries (System.String path, System.String searchPattern, FileAttributes mask, FileAttributes attrs) [0x00000] in <filename unknown>:0 
  at System.IO.Directory.GetFiles (System.String path, System.String searchPattern) [0x00000] in <filename unknown>:0 
  at System.IO.DirectoryInfo.GetFiles (System.String searchPattern) [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.IO.DirectoryInfo:GetFiles (string)
  at CalicoFSharpEngine.GetCalicoLibraries () [0x00000] in <filename unknown>:0 
  at CalicoFSharpEngine.loadAssemblies () [0x00000] in <filename unknown>:0 
  at CalicoFSharpEngine.PostSetup (Calico.MainWindow calico) [0x00000] in <filename unknown>:0 
  at Calico.LanguageManager.PostSetup (Calico.MainWindow calico) [0x00000] in <filename unknown>:0 
  at Calico.MainWindow.ResetShell () [0x00000] in <filename unknown>:0 
  at Calico.MainWindow+<ExecuteFileInBackground>c__AnonStorey18.<>m__0 () [0x00000] in <filename unknown>:0 
  at System.Threading.Thread.StartInternal () [0x00000] in <filename unknown>:0