Added recent changes from codeplex to address a few recent bugs.

See: added simple equivalence check fotsymbolic types:
https://fsharp3sample.codeplex.com/SourceControl/changeset/24323

Add correct base constructor IL op codes:
https://fsharp3sample.codeplex.com/SourceControl/changeset/24356
Merge pull request #553 from 7sharp9/master

Added recent changes from codeplex to address a few recent bugs.
Fix Mono