Modify transactions so nested transactions work
Use default param prefix for SqlExpression's as its converted later.
Add DbType to DatabaseType and use it for parameter
GetType of null for DbType
Properly ignore columns
Add tests for scanned conventions
Fix select columns so that no alias is produced
Remove DbType lookup for null
Refactor sqlexpression query execution
Fix member aliases for sql functions
Allow sql expressions to be a bit more complex
Fix provider name for SQLite
Fix Guid parameters
Fix for DbType.Time not working for SqlServer