Check whether declaration escapes file in ReferenceFinder

Instead of instead of in IdentifierScope
Project.GetContents always returns same result

For a given project. Don't want the contents of a file to change
partway through a refactoring.
Add the possibility to specify initial untyped infos

So that MonoDevelop can pass in TypeCheckResults, avoiding the need to
retypecheck files.
Merge branch 'master' of github.com:Lewix/fsharp-refactor