Fixed Transaction problem with FirebirdTest.
Changed:
using (var db = ConnectionString.OpenDbConnection())
To:
using (var db = new OrmLiteConnectionFactory(ConnectionString, FirebirdDialect.Provider).Open())

With this change the Firebird provider works as expected, at least regarding the use of Transactions.

Also added app.config and changed OrmLiteTestBase.GetFileConnectionString() to use it, to allow an easy connection string setup.
Fixed some more tests and some hardcoded connection strings.
All tests are ok now, except OrmLiteQueryTest.Can_select_with_filter_from_ModelWithOnlyStringFields_table().
db.ByExampleWhere doesn't ignore NULL properties and the query returns 0 rows.