Added latest changes for decimal, DateTime, DateTimeOffset generation from codeplex

See:
https://fsharp3sample.codeplex.com/SourceControl/changeset/24784
https://fsharp3sample.codeplex.com/SourceControl/changeset/24770
https://fsharp3sample.codeplex.com/SourceControl/changeset/24765
Merge pull request #20 from 7sharp9/master

Added latest changes for decimal, DateTime, DateTimeOffset generation from codeplex