Revert "several changes to script abort handling and app domain loading code"

This reverts commit 9b72d652b7a6a44c9dfdf7b0230c2aca3cd21056.

The correct way as per .NET framework specification has unforeseen consequences resulting from the structure of the remaining code.
Merge pull request #2 from ft-/master

Revert "several changes to script abort handling and app domain loading ...