Various fixes

[alex-kulakov]

Contains a bunch of small fixes:

1. Fixes issue when EntithChangeRegistry.Count value becomes corrupted.
2. Fixes reference synchronization during entity removal. Full case represented in IssueJira0792_* file.
3. Addresses an issue when during constraint validation of a lazy-load field its value happens to be fetched even the field isn't changed
4. Removes extra SELECT wrap for cases when TypeId value is the only calculated column in query. There is no point in it. It also fixes an issue when usage of In() extension in filter of bulk operations produces invalid query, for instance

var idsToUpdate = new[] { 99, 100, 102 };
var updatedCount =  session.Query.All<Bar>()
  .Where(b => b.Id.In(idsToUpdate))
  .Update(bar => new Bar(session) { Name = prefix + bar.Name });

[AlexUstinov]

Hi @alex-kulakov
I've notices UnicodeNamesTest is shown as binary file in github (see
https://github.com/DataObjects-NET/dataobjects-net/pull/34/files#diff-f36b0aa3eba6c46119b3b079d36a3ce3).
It doesn't show differences because of this.
Could you please check?

[alex-kulakov]

Seems to be that it is shown as binary after one of PRs merged into the master branch where file encoding was changed. I'll fix it in this PR.

[alex-kulakov]

I have changed encoding for the file to UTF-8 and has to change it to commit but the file is still shows it as binary. Hmmm. Locally the file is threated as a text file though