Resolve #26 - renaming the INHLinqWrapper type to ISessionWrapper

This type was previously released in 2.4.x and so to maintain compatibility it
has been marked obsolete.
Resolve #22 - DynamicSelect types are in incorrect namespace

In fact, these types have not yet been integrated into the project, they are
part of a future issue to work on: #28.

* Moved these source files to a doc directory where they can be picked up and
  worked on later.
Resolve #24 - addition of new TryPreserveStackTrace method for exceptions.