This class is the base class for platform specific progress metering within the ODA Platform. 

Corresponding C++ library: TD_Db

This class receives progress notifications during various database operations such as loading or saving a file. 

Calls to an instance of this class will always come in the following order: 

1. setLimit (called once).
2. start (called once).
3. meterProgress (called repeatedly).
4. stop (called once).