Fix how commands are enrolled to connections in CRUD operations

Use existing DbConnection on DbCommand object if present

 - Then previous usage: connection param if provided, then new local connection.
 - Fixes Scalar used in Insert within transaction.

-> 3.2.0

-> 3.2.0-alpha; update CHANGELOG

-> 3.1.3 + changelog

Merge branch '3.1.2'

Improved NuGet package message